The single most important aid to mushrooming, says Kent McKnight, a research botanist with the USDA, and one of the founding members of the Washington Mycological Association, is "to find someone who knows their mushrooms."

"Do not under any circumstances eat anything you're absolutely not sure of," he says, adding that "the penalty may be pretty big."

As a rule, note veteran foragers, it's equally wise to consult several guides for positive identification. Among some of the most reliable sources for beginners, notes McKnight, are the works of Alexander Smith -- "A Field Guide to Western Mushrooms" (University of Michigan Press, 1975) and "The Mushroom Hunter's Field Guide: All Color and Enlarged" (University of Michigan Press, 1980), Orson K. Miller Jr.'s "Mushrooms of North America" (Dutton, 1979), and L.R. Hesler's "Mushrooms of the Great Smokies" (University of Tennesssee Press, 1960).

For further information on the activities of the Mycological Association of Washington, write to Bill Waller, 2A West Loudon, Leesburg, Va., 22075. Subscription to the organization's bi-monthly (except July-August) newsletter, "Capitol Mushrumors" is $10 (individual) and $15 (family) and includes membership. Sample copies are $1. (Queries may be sent to the above address.)

McKnight claims to have no difficulty in finding specimens -- nor do area mushroomers, who attest to the validity of the national club's motto, "Discover a World of Wonder at Your Feet." But for those of us who'd rather forage for our mushrooms from the shelves of local markets, here's a partial listing of where to look:

Columbia Plaza Gourmet (538 23rd St. N.W.) -- Carries fresh, depending upon availability: chanterelles, enokis, trumpet, shiitake; carries dried: porcini, cepe, chanterelle, morels.

Giant -- Carries the following fresh mushrooms on "a regular, seasonal basis": chanterelle, gypsy, oyster, shiitake, wood ear.

Larimer's (1727 Conn. Ave. NW) -- Carries enoki, shiitake and button mushrooms.

Mikado Grocery (4709 Wisconsin Ave., N.W.) -- Carries fresh enoki and dried Chinese and black mushrooms.

Neam's (3217 P St. NW.) -- Carries shiitake, button mushrooms and, periodicaly, chanterelles.

Oriental Supermarket (in the Wintergreen Plaza at 891 F Rockville Pike, Rockville, Md.) -- Carries dried shiitake, black mushrooms; Carries canned oyster, golden and straw mushrooms.

Safeway -- Currently in the process of promoting a variety of mushrooms, Safeway recently offered weekly specials of oyster and shiitakes. A select number of stores also carry chanterelles, enoki and trumpet mushrooms.

Sutton Place Gourmet (3201 New Mexico Ave. N.W. and 10323 Old Georgetown Road in Bethesda) -- Carries eight varieties of dried mushrooms: cepes, Italian and French morels, morillons, mousserons, champignon noirs, porcini, Chinese mushrooms. Fresh mushrooms include shiitake, oyster, enoki, chicken of the woods, lobster, chanterelle, wood ears, morels, porcini, (occassionally) puff balls.

The French Market (1632 Wisconsin Ave., N.W.) -- Carries fresh: shiitake and chanterelles (in season). Carries dried cepes, morels, chanterelles.