NANCY AND Ronald Reagan ate veal virtually morning, noon and night during the inauguration festivities. Once in the White House, they ate medallions of veal marsala at the state luncheon for the Prime Minister of Japan, and veal farci at the President's private 70th birthday party.

But when Nancy Reagan went to lunch at Evangeline Bruce's home to meet some of the Washington ladies, she was finally served something different.

Helen Wasserman, the owner of Chez Wok, catered the private lunch for six and she prepared a clear soup with sliced vegetables, scallops with french cucumbers in a white sauce, brown rice with a puree of carrots, snow peas with slivered sweet red peppers and for dessert: papaya with a kiwi sorbet.

Just before the Reagan inauguration Jody Powell, former President Carter's press secretary, said that if he had the whole Carter administration to do over again, he would arrange for the Carters to get to know "old Washington" and the media heavies.

Apparently the Reagans don't intend to make the same mistake.

Not only have they been courting Washington at well-publicized dinners, but Mrs. Reagan has been slipping out of the White House for small, private luncheons like the one at Mrs. Bruce's house Jan. 30.

That luncheon came about when the First Lady called Mrs. Bruce, said she had always admired her and asked to meet some of Mrs. Bruce's friends.

At the Bruce lunch were, in addition to the hostess and Mrs. Reagan, Lorraine Cooper, Patricia Haig, Susan Mary Alsop and Jessica Catto.

In the words of one of the women, who asked not to be named, "all of us have known each other a very long time and the lunch was very low key, very interesting." All, citing the wishes of the White House to keep the lunch private, refused to say more.

Mrs. Wasserman, who has been catering in Washington for three years and has done several dinners for Mrs. Bruce before, said she received a call from Mrs. Bruce two nights before the lunch, saying that Mrs. Reagan was coming for lunch and could she cook?

"Mrs. Bruce wanted the lunch to be very informal, very light and very elegant," Mrs. Wasserman said. "We worked the menu out together and she was in contact with the White House to make sure Mrs. Reagan liked all the things we were serving."

Los Angeles florist Stanley Kersten, who is a favorite of Nancy Reagan and other women in "The Group," got a Gucci billford in the mail the other day as a thank you from the First Lady for all he did in Washington during the inauguration.

She signed the accompanying note, as she does all such personal messages, not with "Nancy" or "Mrs. Reagan."

She drew a round little "happy face."

Everyone, including a spokesperson for Joan Kennedy, denies that there is anyone who would like to see her resign as chairman of this year's upcoming Washington Opera Ball.

Mrs. Kennedy was picked, as is the annual custom, last summer, when it looked like there might be a Democrat in the White House.

Last June, Nancy Kissinger hosted the ball, even though there were Democrats in the White House and it didn't seem to make a difference. But some of the Reagan's friends are said to be upset over the fact that the chairman isn't a Republican and they aren't sure whether they will participate in surrounding festivities if Mrs. Kennedy doesn't resign.

Out in Palm Springs, where the desert is coral-colored, the newly appointed U.S. Chief of Protocol, Lee Annenberg, is famous for wearing coral colored gowns.

So when she showed up recently at a Frank Sinatra retrospective at the arts museum wearing "Reagan Red" all her Western neighbors decided then and there she was Washington bound.

Some Sinatra watchers in Palm Springs are convinced that Sinatra has more to gain than just a gambling license in Nevada if his current efforts in that state are successful.

One source close to Sinatra said last week that if he is successful, that stamp of approval could clear the way for him to try for an ambassadorship in the Reagan administration.