Linda Kaufman steps up to her 18th-century mahogany sideboard and opens a door to show off its authenticity: a label from its New York cabinetmakers, William Mills and Simeon Deming. Across the four high-ceilinged rooms in the National Gallery of Art’s West Building, there are more than 100 priceless finds like this one, each her gift to the nation. All the pieces are lit up in a new home, and in her mind’s eye she sees “kids, riding by on tricycles, on a rainy afternoon.”

Kaufman and her late husband, George, let their two children have the run of their Norfolk riverside mansion, and later their four grandsons. Fine antiques have lived there but so, too, has a family. Her collector friends and antique curators obsessed over the trends in markets and scholarship, “but we were raising children and dogs,” Kaufman recalls.

Of course, children sometimes leaned back in chairs, which sometimes snapped. She just took them to repair shops. “They made it through 200 years,” she says, “they can make it through me.” In drawers and on cabinet shelves, she stacked everyday belongings. “In that one, I put sweaters,” she points out, “and over there, pillowcases and sheets.”

Inside the house, a replica of Andrew Jackson’s Hermitage, valuables were never cordoned off, but the collection is still a showcase of refinement, like Kaufman herself. “We always like the more sophisticated pieces,” she says. “I’m just not a very folksy person.” And yet wherever she passes in the National Gallery, curators and security guards call out to her — always “Linda.” She keeps herself done up — black pantsuit and butterfly pin — but ready for a day with art handlers, with her salt-and-pepper hair in a Tidewater-gentlelady bun.

She’s the daughter of wealthy Old Dominion philanthropists and the widow of an entrepreneur who founded the Guest Quarters hotel chain. This furniture donation may be the family’s most heroic act of hospitality. She wants everyone to see what she and George found, a treasury of historic pieces that was “one of the largest and most refined collections” in private hands, according to the gallery. And all their work to preserve these valuables was its own act of creativity and ingenuity.

Desk and Bookcase, 1755-1765 mahogany, yellow pine, white cedar, poplar, white oak. (Courtesy National Gallery of Art, Washington, Promised Gift of George M. and Linda H. Kaufman)

Kaufman collects what is called the decorative arts, a fussy name for a messy process in which a lot of sawdust flies. This was a craft for a nation that was literally building itself by hand. Early American furniture like the pieces the Kaufmans found — representing crucial city styles from Boston to Baltimore, in the colonial, federal and classical periods — is considered colonial America’s first art form.

Many of the Kaufmans’ pieces have been on view before; the National Gallery showed several rooms of their furniture in 1986. That exhibit felt like an American answer to the Treasure Houses of Great Britain blockbuster that captivated museumgoers a year earlier.

This new display has a septuagenarian grandmother’s touches. White orchids will brighten tabletops, which Kaufman long ago figured out to be a necessity. (“One day, I turned to my husband and said, ‘George, something’s missing,’ ” she recalls.) She may move out one Chippendale side chair for a pretty painted one. She will futz — but not much, since she and George have had their fun with arranging, which has been as much fun as purchasing, she says.

When a piece arrived, “we’d tend to put it at the foot of our bed,” she says. “It’d be the first thing we saw in the morning and the last thing we saw at night.” They moved everything around, all the time. “In 50 years, we’ve pretty much tried everything.”

The Kaufmans purchased most of their pieces from a legendary Manhattan dealer, Israel Sack, and other pieces at auction in New York. In the 1980s, buying was a buzzy, competitive bazaar, mixed with a social swirl. Collectors knew each other. They dined together before a sale and discussed what they wanted. After the last lot was gaveled “sold,” they reconvened, sorting out who had scored a steal and who had bagged a turkey.

Kaufman imposed a rule: She would try never to bid against a close friend. “I’d rather have a friend than a piece,” she says. When bidding on furniture, fewer intimates would have auction-house paddles in play.

“George liked to go up and sit in the balcony,” recalls Dean Failey, who oversaw American furniture sales at Christie’s for decades. George Kaufman and fellow collectors would debate what made each piece valuable, beyond its perfect condition and impeccable craftsmanship. Was a block-and-shell chest from Newport better if it had three drawers or four? George Kaufman insisted three. It was an aesthetic formula of his devising, about proportion, about expression, about strength.

“George was right in front of the pack, with his business acumen,” Failey says. “He really was the lead horse for a good number of years, and that’s principally when the large amount of their collecting took place.”

For decades, the Kaufmans welcomed Winterthur curator Wendy Cooper to see what they found, hosting her in Norfolk for many visits. Ultimately, Linda Kaufman and the National Gallery invited Cooper to guest-curate the collection as it becomes a permanent fixture in Washington.

Cooper remembers their enthusiasm most of all. “Look at that great foot! Look at that inlaid top,” she recalls George Kaufman saying. Nothing felt too precious in their house. George smoked. Guests put drinks on table surfaces, protected under glass tops. “They never made anyone feel like they couldn’t sit on a chair or a sofa,” Cooper says.

If Washington hasn’t yet become a destination for the Americana madness of recent years, it’s about to be. Some good furniture is on display in Williamsburg and Mount Vernon, and even finer examples are in the White House and the Diplomatic Reception Rooms at the State Department. The pieces that the Kaufmans gathered are the highest of the high end — not a blanket chest nor painted-Indian motif in the lot. And they represent a recent heyday in auctioneering.

The early-American antiques market percolated in 1972 with a $100,000 purchase, by Doris Duke, of a Rhode Island highboy. “News spread like prairie fire,” Failey, the Christie’s expert, recalls. The numbers climbed, and Failey sold the first piece to top the million-dollar mark: a Philadelphia scallop-top tea table. “Today it’s not common, but it isn’t unusual, for a piece to sell for a million or well over a million.”

Reality crews are now in the chase. Deal-hunter TV shows dominate the cable ratings, with “American Pickers” raiding barns and attics for rarities. That's not Kaufman’s terrain. “I’m not much good at junk shops,” she says.

She has found pieces, and pieces have found her. Two decades ago, she and George received a FedEx package from their friend Leslie Keno, one half of the identical-twin appraisers on “Antiques Roadshow.” His note: “Look what we found!”

Decades before, a woman in New Jersey had admired a demilune table at a yard sale. The buyer plunked down all the cash she had in her pocket, a mere $25, even though the asking price was $30. She gently took off some mold with turpentine, used the table and, much later, she took it to the PBS series’s open call. The Kenos peeled back some Christmas wrapping paper protecting its underside. There was a label from John and Thomas Seymour, the father-and-son makers who had emigrated from England to Boston. Both Kenos knew that the Kaufmans owned one and thought they had found the perfect mate. “It would be as if Leslie and I had been separated,” Leigh Keno jokes.

The Kaufmans decided to pass. But at auction, the card table found a home, for $541,000, a record at the time. And to top it off, the makers’ name matched that of its new owner, the supermodel Stephanie Seymour, whose art-collecting husband, Peter Brant, bought it for her.

By the late 1990s, the market softened. The Kaufmans’ coterie dissipated — no more dinner parties where George would take up a host’s challenge to arrange all the chairs in a collector’s apartment in order of their worth. He died in 2001, at age 69. Today, auctions attract many secretive players, who often chime in via cellphone.

“It’s disappointing that I don’t see younger people bidding,” Kaufman says. “People are scared off by the very high prices.”

Pieces of worth still turn up. “Wonderful objects that may not be masterpieces, they’re out there,” Failey says. “It’s a bargain.”

At the museum, Kaufman beckons a preparator and a registrar, who are putting on gloves to handle what she has “tossed around” for years, she notes. “Let’s play a minute,” she tells the women.

She has just purchased a pair of Bristol blue glass decanters. They look like cobalt, and one has a label reading “RUM” and the other “HOLLANDS,” which she takes to mean gin. She’s arranging them on her sideboard, pulling at the little stoppers, which are marked H and R. She’s having fun.

She points to a yellow Grecian couch, the only piece she bought in Washington and a perfect example of Baltimore painted furniture, with brush strokes mimicking gilding and rosewood. Her daughters and granddaughters used to lie there, posing for photographs as if they were napping on it.

Kaufman has guided the curators to make the place look less like a museum, urging a rethinking of an array of portraits flanking her sconces and looking glasses. “It was one man after another, each in black coats,” she says. Instead, she helped choose women who were dressed more colorfully and added to the domestic vibe. One she liked because the subject posed with a little dog, and Kaufman relates. (Asked what kind of dog she likes, she says, “the barkless kind.”)

“We’re just trying to show things in the home context,” she says, walking over to a desk and chest, again by the Seymours. Its pointy top compartment has a fold-down door. “Here’s where you could store your tricorn hat,” she teases. A green writing surface appears when she unfolds the desk. “I served coffee on this many, many times.”

The gallery sent six trucks to load up her pieces. She was surprisingly elated to see them go. “I thought I would be tearful,” she says. “Now that they’re in the National Gallery’s hands, they never had it so good.”

Masterpieces of American Furniture from the Kaufman Collection, 1700-1830

on display indefinitely at the National Gallery of Art, West Building, Fourth Street and Constitution Avenue NW. 202-737-4215. .