The mysterious and delightful donation had arrived in Washington - some 50,000 pounds of frozen ravioli and pizza - and by yesterday the Italian delicacies were being handed out free to the needy and not-so-needy by city dignitaries, including Del. Walter E. Fauntroy (D-D.C.).

Although the 2,800 cases of ravioli and 600 cartons of pizza were meant to help tide the poor through the winter, some of the recipients apparently were far from destitute. Among those who picked up free food at Fauntroy's office yesterday was a number of General Accounting Office employes, lured by radio announcements.

"There were fights out here when they tried to give it out," Patricia Johnson, a volunteer worker for the House of Ruth, a charitable organization, said last night at Fauntroy's office at 441 G St. NW.

The House of Ruth, officials said last night, arranged to pick up the food from an anonymous manufacturer, bring it here by truck from a warehouse in Secaucus, N.J., and have it stored here in refrigerated quarters.

Cecelia Cunilio, an administrative assistant at the House of Ruth, said the ravioli and pizza giveaway began with an unexpected telephone call from Synanon, a California-based narcotics treatment organization. A Synanon official, Cunilio said, asked whether the House of Ruth could help distribute surplus food and other commodities, and the House of Ruth agreed.

Synanon officials could not be reached for comment last night.

What followed, Cunilio said, was a series of elaborate plans to pick up the frozen ravioli and pizza from a manufacturer in Hackensack, N.J., and distribute it to charitable groups and needy persons in the Washington area. Although she said the manufacturer asked to remain anonymous, the pizza and ravioli boxes were labeled with the name Buitoni Foods Corp., of South Hackensack.

"I don't know if it's some kind of tax write-off or what," Cunilio said. "It's good qualtiy food. It's not old food."