Just how well do you want to know your vegetables? Would you feel better if you knew their backgrounds? Their pedigrees? What if you could see their baby pictures?

If this sounds interesting, then head for the farmers' market at either the National Institutes of Health in Bethesda on Tuesdays or the National Institute of Standards and Technology in Gaithersburg on Thursdays and queue up at the table of Renee Spates.

There, in addition to her radishes, carrots, scallions, lettuce, chives and chive blossoms, and lovely spinach, Spates has an album of photographs of her Poolesville fields. Indeed, you can ask to see the very patch from which your spinach sprung.

This is the sort of experience that lures customers all around the Washington area to their local outdoor farmers' markets and makes them wonder about the ones just over the hill or across the river. To save everyone some time, we've visited most all of them and this is what we've learned.

District of Columbia

Adams-Morgan: Smack in the center of the bustle that is Saturday in Adams-Morgan sits a farmers' market of considerable diversity that belies its small size. There is an admirable range of produce -- some organic rhubarb and mint on a recent visit, apples, tomatoes, spinach, peas, potatoes, free-range or double-yolked eggs, homemade breads and cakes, yogurt and cheddar cheeses and jellies. In addition to an organic mind-set, one vendor also emphasized recycling of cardboard egg crates, paper bags and such.

Saturdays, all day, all year, at Columbia Road and 18th Street NW, in front of the Perpetual Bank, 678-2800.

Anacostia: The market will open when produce is available.

Sundays, 7 a.m.-1 p.m., until Dec. 22, parking lot of the D.C. Lottery Board, Martin Luther King, Jr. Avenue and W Street SE, 678-2800.

D.C. Open Air: With the vibration of Metrorail above and the smell from the barbecue and fried fish vendors below, the District's largest farmers' market is a bustling urban island. Forget about just plain old lettuce; this is the place to stock up on greens such as collards, mustard, kale, spinach and poke. It's also pig heaven: slabs of thick country bacon, crisp-edged bacon skins, smoked bacon ends and smoked pork shoulders.

Tuesdays and Thursdays, 7 a.m.-6 p.m.; Saturdays, 6 a.m.-4 p.m., all year, Oklahoma Avenue and Benning Road NE, near RFK Stadium in parking lot No. 6, 678-2800.

Eastern Market: This Capitol Hill market operates five days a week but on Saturday farmers and a sidewalk full of vendors join together outside the red brick building to sell jewelry, slightly battered furniture, other collectibles and produce. The block itself has a number of stores that are good for browsing, as well as a couple of sidewalk cafes. There's plenty of life inside the market, too. Refrigerator cases showcase smoked jowls, loose sausage meat, fresh fish, extra-lean oxtail and fresh chicken parts. Shoppers can also buy a D.C. Lottery ticket, or hot food to go: omelets or a scrapple and egg sandwich for breakfast, and barbecue, crab cakes or fish platters for lunch.

Saturdays, 7 a.m.-5 p.m., North Carolina Avenue and 7th Street, SE, all year, 543-7293 for questions.

Maryland

Anne Arundel County: The sun beats down hard on the pavement, but a pavilion nicely shades more than 20 stalls in this neat and organized market. The produce is terrific: rugged-looking patty pan squash, boxes of dark blackberries, and most welcome of all, deep red, juicy and flavorful tomatoes. Get there early before all the best produce is gone. Wooden puzzles for children and jars of jam flesh out the offerings.

Saturdays and Tuesdays, 7 a.m.-2 p.m., until Dec. 8., Riva Road and Harry S Truman Parkway, Annapolis, 222-7434.

Cheltenham: In addition to fresh produce locally grown, look for Amish baked goods and for homemade jams from TGIF ("Thank God It's Fresh") Farm in Croom. The market has space for 28 vendors.

Tuesdays and Thursdays, 3-7 p.m.; Saturdays, 9 a.m.-5 p.m., until late October, Route 301, nine miles south of Upper Marlboro, 301-372-1066 or 1-800-533-FARM.

College Park Farmer's Market: This small, unpretentious marketplace is suffering this summer from construction at a railroad crossing on Calvert Road that has severed the main artery, discouraging both farmers and customers from participating. In addition, to standard summer garden fare, there was a small flower stand on a recent Saturday that was a standout with cheerful sunflowers, elegant lilies and colorful summer perennials at reasonable country prices.

Saturdays, 7 a.m.-noon, through Oct. 27, NMCPPD swimming pool lot, 5211 Calvert Rd. (Calvert is closed from Route 1, reach market from east via Kenilworth Avenue), 301-567-4375.

Indian Head: The season started slowly with only one farmer/vendor in place under the trees near the Naval Ordnance Station but assurances have been given that the pace will pick up as local produce ripens. At least it's a pleasant drive and offers an excuse to indulge in some of the area's best barbecue joints along the way in Charles County.

Tuesdays and Thursdays, 10 a.m.-1:30 p.m., on the Indian Head village green at the end of Route 210, 301-743-5511.

La Plata: Like a truck farm in the middle of a parking lot, the Charles County growers at this market sell their wares off the backs of their pick-up vehicles. It's not a big market, but the atmosphere is friendly and laid-back, and there are some specialty produce items available, including yellow tomatoes.

Wednesdays, 3 p.m.-7 p.m.; Saturdays, 8 a.m.-3 p.m., until mid-November, Charles Street and Washington Avenue, 301-934-8345.

Montgomery Farm Women's Coop: This market is one of the few remaining reminders of the old Bethesda -- of even 10 years ago. Inside, however, the market has found produce growers and grocers giving way to upscale bakery counters, Chinese fast food vendors and trays full of costume jewelry. Plants, flowers, crafts and toys are also for sale and, in true Montgomery County fashion, there's sometimes a bit of politicking outside, so visitors may be able to register to vote and shop for rhubarb at the same time.

Wednesdays and Saturdays, 7 a.m.-3 p.m., all year except holidays, 7155 Wisconsin Ave., Bethesda, 652-2291.

National Institutes of Health: The market is small -- only four or five organic growers and some baked goods -- but these farmers sell only their own produce and it's all grown in Montgomery County. The only catch is that you must want some produce badly enough to hunt a bit for it. Persist, you'll find it -- eventually. Be prepared to wander around the serpentine roads of the complex and don't be shy about asking directions. The signs are vague and inadequate and the market is at the far end of one of many parking lots -- listed as lot 41B.

Tuesdays, 2-6 p.m., until Nov. 6, on parking lot 41B, enter NIH either off Wisconsin Avenue or Old Georgetown Road, 217-2345.

National Institute of Standards and Technology: Like its sister market at NIH, this one is tucked under some trees in the middle of a parking lot not far off I-270, but due to better signage, it is far easier to locate. Recently the wide selection of peas, from snow to sugar to English, made the trip up-county worthwhile.

Thursdays, 2-6 p.m., until Nov. 1, I-270 and Clopper Road, on parking lot of building 226, 217-2345.

Rockville: With inviting red and white tents across the street from the Rockville Metro station, this location has possibilities. However, pickings of late from the half dozen vendors have been extremely thin with a mishmash of crystals and medicinal herbs, shortbread, some peaches and flowers.

Wednesdays, 11 a.m.-2 p.m.; Saturdays, 9 a.m.-1 p.m., until Sept. 29, Middle Lane across from the Metro station, 424-8000.

Silver Spring: Located in the little square outside the Silver Spring Armory, the market probably benefits as much from visitors to weekend events inside the building as from its location in the heart of downtown Silver Spring. While the area is short on country charm, the market is a shady oasis from which to pick spinach, tomatoes and other produce from folding tables while the traffic buzzes by. Metered street parking available.

Saturdays, 7 a.m.-1 p.m., until Nov. 3, Fenton Street and Pershing Avenue, 217-2345.

Takoma Park: Like Main Street U.S.A. with a hippie/yuppie twist, this friendly, familial market stocks high quality and often unusual produce. There are a few organic farmers, some interesting herb growers and Takoma Kitchens' baked goods. There can be long lines, particularly during the first couple hours of the market, but nobody seems to mind. Neither do the kids with strawberry-stained faces.

Sundays, 10 a.m.-2 p.m. until Nov. 18, Laurel Avenue between Eastern and Carroll Avenues, 248-8572 or 270-1700.

Waldorf: Surrounded by antiseptic new shopping malls, this oasis of fresh produce on busy Route 301 is an odd but welcome sight. There were only a half dozen vendors on this early season Saturday (including one selling live blue crabs and an Amish family selling great homemade dinner rolls), so it's not the kind of place you'd make a special trip to unless you live in the neighborhood or happen to be at Hecht's.

Saturdays, 8 a.m.-noon, until Oct. 27, Route 301 and Smallwood Drive on the community park-and-ride across from new regional mall, 301-932-6751.

Virginia

Alexandria: More bazaar than market, Alexandria does offer produce, but also everything from stuffed animals to wooden toys and bird houses to quilts. Vendors are arrayed around the plaza pool, which makes the market a popular and picturesque spot for early risers to start the weekend with coffee and some of the baked goods on sale.

Saturdays, 5-9 a.m., all year, 301 King St., City Hall Plaza, 838-4770.

Arlington: Jam-packed with shoppers in the early morning, this market makes even the busiest supermarket look deserted. More than two dozen vendors sell an amazing variety of vegetables, plants and baked goods, making it difficult to decide not only what to buy but from whom. Despite the large number of vendors and goods, prices are not low. Recently, several farmers were selling tomatoes for $3 a pound -- and people were lined up to buy. Parking is a challenge, especially since the outdoor municipal lot across from the old court house has been closed.

Saturdays, 7 a.m-noon., until Dec. 16, Courthouse Square, 358-6400.

Burke Centre: One of five producer-only markets (also Fairfax, Herndon, McLean, Mt. Vernon) run by the extension service in Fairfax County, this is a no-nonsense operation. At least half of the vendors are vegetable and/or fruit operations and the rest sell baked goods, plants, flowers and even shiitake mushrooms. Parking is good.

Saturdays, 8 a.m.-noon, until Nov. 17, K-Mart parking lot, Burke Center Parkway and Roberts Parkway, 246-5390 for recorded information.

Dale City: There's plenty of room here for the vendors to set up, and consequently almost two dozen of them do, selling an impressive array of produce, perennials and baked goods out of everything from little pickup trucks to large counters on wheels with tent tops. There's plenty of room to park, too.

Sundays, 9 a.m.-1 p.m., until Oct. 28, Dale Boulevard and Gemini Way, VDOT Minnieville fringe parking lot, 703-335-6285.

Fairfax: This is typical of the Fairfax extension markets with well over a dozen vendors and strength in produce, but things will change with the move in August from Fairfax High School to Draper Park. Vendors complain that parking isn't as good and customers complain that accessibility isn't as good.

Wednesdays, 9 a.m.-1 p.m., until Aug. 15 at Fairfax High School, 3500 Old Lee Hwy., Aug. 22-Nov. 14 at Draper Park, Route 50 west of Fairfax Circle, 246-5390 for recorded information.

Falls Church: The normally tranquil Falls Church City Hall comes alive with color and people on summer Saturday mornings as some two dozen vendors sell a wide array of luscious looking (and tasting) produce to a stand-up crowd, with many eager buyers lining up even before the market opens. Unique to the Falls Church market is a Granny Crump's Delectable Delights brownie stand that should not be missed by cookie lovers.

Saturdays, 8 a.m.-noon, until Oct. 28, 300 Park Ave., 241-5027.

Fredericksburg: A dozen trucks can parallel park along the curb next to Hurkamp Park and if more vendors are there they park across the street. This is a nitty-gritty collection of farmers, no arts, no crafts, just good ingredients for dinner and perhaps some fresh munching under the trees in the park, plus some plants and baked goods.

Mondays-Saturdays, 6 a.m.-6 p.m., all year, Prince Edward Street between George and William streets, 703-372-1010.

Herndon: This is the place for those shoppers who can't wait until they get home to sample their goods. More than a dozen stands (one quarter selling baked goods; the rest, produce) administered by the extension service are set up just a few feet away from an inviting, shady patch of grass. Or, find a more secluded spot on the Washington & Old Dominion Trail that passes by the market. Helping the eat-on-the-spot urge is a soft-drink stand -- a joint venture of the nonprofit Downtown Herndon Inc. and the local high school's sophomore class.

Thursdays, 9:30 a.m.-1 p.m., until Nov. 1, Spring Street next to Herndon Town Center, 246-5390 for recorded information.

Leesburg: The Leesburg market is kind of like a Loudoun County village -- just a few folks and everybody seems to know everybody else. This producers-only market features mostly produce from farms west of Leesburg. Hetzel's Family Farms and Wheatland Vegetable Farms of Purcellville and Mill Road Farm Inc. of Leesburg are among them.

Look for potatoes, kale, heads of cabbage the size of a bowling ball, a variety of herbs, snap green beans and large, crisp beets. The beets, especially, tend to sell out early.

If you like to barbecue, there is also some fresh beef to be had from nearby cattle farms. And some personal touches -- fresh-squeezed lemonade, tangy and ice-cold from Hetzel's Family Farms, and a free booklet of summer recipes and diet tips from Susan Planck of Wheatland Vegetable Farms.

Saturdays, 9 a.m-1 p.m., until Oct. 27, Leesburg Plaza, Market Street, 703-777-1262.

Manassas City: The pace is relaxing here in the historic downtown. Unlike the more frenetic pace of markets closer to the city, there are rarely any lines or harried customers. Mothers pushing strollers or senior citizens are the main customers -- until 11 a.m. when employees from a nearby IBM office stop by to pick up some goodies to go with lunch that many eat at a small, nearby gazebo. Although eager shoppers arrive early to grab the best produce, many vendors still are left with a plentiful supply well into the morning.

Thursdays, 7:30-1 p.m., until Nov. 1, Center & West streets (gazebo area), 703-335-6285.

McLean: This extension service market is relatively small -- about a dozen vendors in a corner of a parking lot of a county park. Still, it offers a plentiful choice of produce and is so busy, especially in its first hour, that it can be difficult to get in and out of the parking lot and even more challenging to find a space. The pace quiets down substantially as the morning wears on, but then it may be too late, particularly if it is berries you are after.

Fridays, 9 a.m.-1 p.m., until Nov. 1. Lewinsville Park off Chain Bridge Road, 246-5390 for recorded information.

Mt. Vernon: The best thing about this market is that it's run by the county extension service and is strong on fruits and vegetables. The worst thing is that it's at a county government complex and weak on empty parking slots.

Tuesdays, 9 a.m.-1 p.m., Parkers Lane at Sherwood Hall Lane, Mt. Vernon Governmental Center parking lot, 246-5390 for recorded information.

Sterling: Perhaps it's the proximity to some of Virginia's best farmland that makes the offerings at this market unusual. In addition to the usual array of produce and a lone baked goods stand, there also is a winery stand, two "natural" beef stands and two herb stands. Activity is brisk, as cars pour in and out of the shopping center parking lot most of the morning.

Sundays, 9:30 a.m.-1:30 p.m, until Nov. 11, Countryside Shopping Center, Route 7 and Countryside Boulevard, 703-777-0426.

Warrenton: Located in a corner of a municipal parking lot in historic downtown, this market reflects the town's quiet country life. Gone are the lines and hustle and bustle found in many markets closer to Washington, making it easier for shoppers to chat with the dozen farmers who sell the usual array of produce, flowers, relish and baked goods.

Wednesdays and Saturdays, 7 a.m.-1 p.m., through December, 5th and Lee streets, 703-347-1101.

Winchester: Half a dozen or so farmers circle their wagons in the middle of the main street of the Old Town center of this historic city. No need to worry about dodging the traffic, though, because Winchester has coverted its main drag into a pedestrian mall while keeping yesterday's sense of a small town intact. No upscale boutiques here; McCrory's still dominates, along with the hardware store, a few antique shops, an art gallery and several little coffee shops, bakeries and delicatessens. Follow signs to the public garage (25 cents) and stroll into a quieter realm past new potatoes, scallions, beets, raspberries, lettuce, flowers, jams and baked goods.

Tuesdays, Thursdays and Saturdays, 7 a.m.-1 p.m., until Oct. 31, Old Town Winchester, 703-662-0963.

Staff writers Kristin Eddy, Bob Kelleter, Maria Koklanaris, Caroline E. Mayer, Eugene L. Meyer, Mollie Moore, Ronalie C. Peterson and Carole Sugarman contributed to this article.