When a valuable Joseph Stella painting was donated to the Hirshhorn Museum last week by the Federal Bureau of Investigation, another case was closed in the FBI's National Stolen Art File. Some less valuable art the FBI has obtained through investigations of fraud, forgery or theft will go on view May 15 at the McIntosh/Drysdale Gallery. The show, "The F.B.I. Collects," features works from various FBI field office files.

McIntosh/Drysdale will be transformed into a sort-of Rogues' Gallery, with fakes purported to be painted by Mary Cassatt, Pablo Picasso, Edvard Munch and others on view. An unauthorized edition of Georgia O'Keeffe lithographs that were sold as signed O'Keeffes by a nephew of her husband Alfred Stieglitz also will be displayed.

Only one painting in the exhibit, an untitled work by Anton Mauve, a relative of Vincent van Gogh, was actually created by the artist who signed the work. Its rightful owner is unknown, and the FBI wants to donate it to the National Gallery of Art after the exhibit closes. The gallery is still considering whether it will accept the donation, says FBI special agent Tom Spitzer.

The National Stolen Art File functions as a "central repository for information on stolen and recovered art objects," explains Spitzer. It is designed for use only by law enforcement agencies, not museums or galleries looking for information on artwork.

"Up until recently, law enforcement did not have a central database on stolen art," says Spitzer. Stolen artwork was "treated like a television or a radio."

That this is an unusual endeavor does not escape McIntosh/Drysdale Gallery Director Nancy Drysdale, who says that while the show was being set up, and the paintings transported from the FBI's Hoover building to her gallery, she glimpsed a strange sight traveling toward her: four FBI agents, with their badges, escorting a grocery cart of framed paintings down the street.

The show runs through June 18. Fundraisers

Spring is the time for benefit functions. The Washington Project for the Arts, not to be outdone, is celebrating its 10th anniversary with an "Ultramarine" bash. "A Phantasmic Undersea Carnival in Day-Glo" reads the invitation. "Dress: Tropical Sleaze, fish masks, fish heads, fish costumes, fishnet . . . Day Glo anything." It all takes place May 31 at the Yale Steam Laundry Building, 437 New York Ave. NW, where guests will also find, "Actual Weirdness/Icky Tableaux," along with the de rigueur cash bar and a raffle. Tickets range from $10 to $75 a person. Call 347-4813 for reservations . . . Also raising funds this month are the Theater Chamber Players, the resident mixed chamber music ensemble of the Kennedy Center. The evening of music, called "Musical Recreations," is scheduled May 16 at 7106 Arrowood Rd., Bethesda. Included on the program will be a performance of Eric Satie's "Sports et Divertissements" with Evelyn Hayes on piano and Patrick Hayes narrating. Tickets are $50. Call 362-8068 for reservations . . . The D.C. Preservation League's coffers will benefit from sales Saturday and Sunday at the annual Georgetown Arts Fair in the Riggs Bank parking lot, 1201 Wisconsin Ave. NW, where the the work of 50 artists will be featured. Sign of the Times

The electronic signboard at 20th and Q streets NW will become a part of the Corcoran Gallery's "SPECTRUM: In Other Words" show, the third in a series of contemporary exhibits, beginning Saturday. The focus of "In Other Words" is contemporary artists' use of language in their work. One of the 10 -- wordsmith/artist Jenny Holzer -- is about to see her work up in lights. Holzer developed "Truisms" in 1983; it's a series of "several hundred aphoristic pronouncements" that have appeared in New York City on posters and signboards, according to the Corcoran. From May 10 through June 29, "Truisms" will be visible on the signboard at 20th and Q, above the Dupont Circle Metro station, for one minute during every 15-minute cycle, 6 a.m.-11 p.m. Holzer's work promises to leave a more forceful impression after 11 p.m., when it will run continuously until 6 a.m. Arts, Etc.

The series of free public concerts cosponsored by the Washington Performing Arts Society and the Friday Morning Music Club continues at various locations around town. Today at 12:30 p.m., the Silver String Quintet graces Kalorama Park with its melodies. The public will be treated to seven more concerts, by different groups, until the end of May. Call 393-3600 for a schedule . . . Adelyn Breeskin, senior curatorial adviser at the National Museum of American Art, is the recipient of the Washington Art Dealers Association's first Award for Cultural Achievement; the award is given for outstanding scholarly achievements and for personal contribution to the arts. Breeskin, who made impressionist painter Mary Cassatt her lifelong study, will receive the award May 19 . . . "20th Century Classicism" is a lecture series sponsored by the D.C. Preservation League and Gerald D. Hines Interests, May 22-June 24. The series will concentrate on buildings constructed after the resurgence of classical architecture in Washington, such as Union Station. Call 737-1519 for information. Hollywood Exhibit Passes

One excellent way to see the "Hollywood: Legend and Reality" exhibit at the National Museum of American History, through June 15: Free timed passes can be obtained at the pass desk, mall entrance of the museum, for Saturdays and Sundays only. The exhibit is open from 10 a.m.-5:30 p.m. It's worth the extra time; the only thing you won't find in the exhibit is a stuffed Toto.