If the Archives of American Art did not exist, these items might well have ended up in the trash:

A list of artists suggested by Picasso, in his incomparably bad handwriting, for inclusion in the historic Armory Show of 1913;

A ticket indicating that as late as 1954, abstract expressionist painter Franz Kline had to pawn a pair of binoculars for $15.Five years later he bought himself two cars -- a Ferrari and a Thunderbird;

Several photographs by Thomas Eakins, and others of Eakins in the nude;

A photograph of Henry Wadsworth Longfellow and his daughter Edith, taken in 1868 in the Rome studio of American painter G. P. A. Healy, scored for enlargement and inclusion in Healy's 1871 painting "Arch of Titus," now in the Newark Museum.

"You must remember that 25 years ago, when we began, there was virtually no interest in American Art -- no books, no courses and few scholars," said Garnett McCoy, deputy director of the Archives of American Art and head of the Washington headquarters, perched high atop the three-story atrium library of the historic National Portrait Gallery building. The Archives became a bureau of the Smithsonian in 1970.

McCoy yesterday was hoping to make his low-profile organization better known on the occasion of its 25th anniversary. The event also was marked by an elegant dinner at the Portrait Gallery last night, attended by 180 of the 1,800 members -- private citizens who pay $25 to $1,000 each year to support the Archives.

In exchange, they receive the Archives' sprightly and informative quarterly journal, and invitations to participate in some of the most elegant art tours -- foreign and domestic -- now under way. (Two tours, called "Archives Airlifts," will leave for China and one will go to Egypt in the coming months.) Through such trips, auctions and garage sales, Archives boosters in five regional centers raised roughly one third of the $830,000 budget for fiscal 1980.

"The Archives began (in the early 1950s) when Edgar P. Richardson, then director of the Detroit Art Institute, was trying to write a book on the subject of American art and simply couldn't find any original research material on the subject," said McCoy, pointing to one of Richardson's many subsequent books, among the thousands which have since been based on Archives materials.

Since then, some 7 million items dealing with artists as diverse as Copley and Warhol have entered the collection -- letters, journals, business papers, sketchbooks and 100,000 photographs once belonging to American artists, dealers, critics and art organizations. Most have been given by artist's heirs who may (but for the most part do not) take tax deductions for their gifts. "They probably don't have the money for the necessary appraisal," noted an observer.

The Archives has also undertaken an ambitious oral-history project, which now boasts 2,000 interviews with leading artists, art historians and collectors.

The Archives is open only to scholars and researchers. But they have organized a few public exhibitions in the past, most of them at the National Portrait Gallery. These small shows have since been abandoned: "We simply don't have the staff," says McCoy, who with a staff of 11 must concentrate on processing and storing the original material, which is kept in Washington. The entire collection is available on microfilm in the Archives' regional centers in Detroit, New York, San Francisco, Boston and Houston.

Some original Archives material can, however, be seen in conjunction with exhibitions now on view in several American cities, including the regional centers -- which are sharing in the anniversary celebration. A particularly hilarious item now headed for the Metropolitan Museum in New York describes the experience of painter Worthington Whittredge, who posed as George Washington in full regalia for Emanuel Leutze's famous painting of "George Washington Crossing the Delaware": "I stood two hours without moving," he wrote, "and was nearly dead when the operation was over. They poured champagne down my throat and I lived through it."

The celebrants at the dinner last night likewise poured some champagne themselves. Edgar Richardson, Lloyd Goodrich (former director of the Whitney Museum of American Art), A. Hyatt Mayor, (former curator of prints at the Metropolitan Museum), James Thomas Flexner (writer and historian), and Alice Winchester (former editor of Antiques magazine) were presented with the first Archives awards for outstanding contributions to the knowledge of American art history.