For almost eight years one of Washington's most venerable organizations has been lobbying the U.S. Postal Service for a commemorative stamp to mark its 100th anniversary.

In the process the Postal Service has gone through five postmasters general, but members of the Daughters of the American Revolution have persisted. The group's successive presidents-general have gone toe-to-toe to speak with each postmaster general, never relenting on the DAR's case for a stamp.

Next month, the DAR will get its payoff.

It won't be the commemorative stamp its leaders wanted, but it will be a picture post card to be issued Oct. 11 during the organization's centennial celebration.

Because "fraternal organizations" are not supposed to qualify for stamps under the Postal Service's criteria, postal officials point out that the card will not be issued to honor the DAR, but rather two of its buildings in the District, which occupy a block near the White House.

Both the DAR's 88-year-old Memorial Continental Hall, which faces 17th Street NW and, in the same block, the 4,000-seat Constitution Hall, which faces 18th Street NW, are saluted on the cards. Both have been designated as National Historic Landmarks by the Interior Department and are honored in a post card series that pays tribute to historic buildings.

Georgetown University's Healy Hall and Blair House, the presidential guest house on Pennsylvania Avenue, previously were part of the series. But those buildings were pictured on conventional postal cards that sold for 15 cents each.

As part of a new marketing ploy designed to bid for a share of Washington's tourist trade, the DAR buildings are on picture post cards that come complete with an imprinted stamp. The Government Printing Office has printed 3 million of the cards, which will sell for 50 cents each, about the price of most picture postcards with stamps.

Pierre Mion, a Loudoun County artist who painted the first two picture cards issued by the Postal Service -- cards featuring the White House and the Jefferson Memorial -- was recruited for the DAR assignment. One side of the new card features Mion's painting of Memorial Continental Hall, built in 1902 for $50,277. The other side carries a smaller painting of Constitution Hall in the card's stamp area.

The cards will go on sale Oct. 11 in ceremonies in the DAR Museum Gallery, 1776 D St. NW. The 10:30 a.m. dedication, open to the public, will be part of a weeklong DAR celebration.

The organization, which now has 200,000 members in more than 3,000 chapters, has weathered considerable controversy in its first century. Perhaps no event provoked as much controversy as its 1939 decision to deny famed contralto Marian Anderson, a black, use of Constitution Hall on the grounds that "all dates were taken."

The furor that erupted led Eleanor Roosevelt to quit the organization, and the incident cast questions about the organization's commitment to minorities that troubled the DAR for years. Anderson later sang in the hall but not until years after she came to Washington and held a triumphal protest concert on the steps of the Lincoln Memorial.

The DAR, chartered by Congress as the female counterpart to the Sons of the Revolution, subsequently admitted blacks, provided they could prove they were descended from a colonial patriot or someone who fought in the Revolutionary War. The DAR since has published four books on black patriots and one of its genealogists spends most of her time tracing the families of black patriots, said Jane Miles Hemphill, the DAR public relations director.