Tacked up on building walls and in florist shops around Tokyo last week was a Mother's Day poster that quickly became a collector's item for journalists covering the economic summit.

The full-color 20-by-28-inch poster by the Japanese florists association showed First Daughter Patti Davis holding a huge bouquet of flowers behind the greeting, printed in English and Japanese: "To Mother, Nancy Reagan, from Daughter, Patty Reagan."

Beneath that was the inscription, "She may be the first lady but she'll always be a mother to me," and a Patti Davis signature. Davis is the author of "Home Front," a novel about a rebellious president's daughter that reportedly hurt Nancy Reagan's feelings. Yesterday, Davis' agent couldn't be reached for comment about the poster, but Japanese firms frequently hire lesser known American personalities to endorse their products.

Whether by accident or intent, the flower shop at the Okura Hotel, where the Reagans, their White House staff and the White House press corps were billeted, did not display the poster. A spokeswoman for Mrs. Reagan said she doubted that the first lady had seen it during her brief stay in Tokyo.

Back home at Camp David by Mother's Day, Mrs. Reagan found cards signed by President Reagan when she ate breakfast on Sunday. She also received cards, flowers and telephone calls from the five children of U.S. Information Agency Director Charles Z. Wick and his wife Mary Jane, close friends of the Reagans since their California days.

The Reagan children also rose to the occasion, according to Elaine Crispen, Mrs. Reagan's press secretary. "She talked to all the kids," said Crispen, explaining that Ron Reagan called Saturday since he expected to be traveling on Sunday.

The first lady did not, however, get flowers from Davis.

American reporters covering Nancy Reagan's trip to Malaysia and Thailand packed color-coded wardrobes per U.S. Embassy directives in each country. In Malaysia that meant no solid yellow, royal blue or white, and in Thailand, no black or white.

Nothing at all was said about reporters having to be chic. That omission became all too apparent in Bangkok, where Thai reporters covering Mrs. Reagan looked as if they had just stepped off the pages of Vogue or GQ, while U.S. reporters looked as if they'd just stepped out of their suitcases.

Only later was it revealed that Thai reporters also followed a dress code, issued by Thailand's Foreign Ministry. Besides Thai silk, Thailand also has a very fashionable queen, Sirikit, who may have enhanced her international reputation further by giving Thai silk scarfs bearing her signature to the media.

Press secretary Elaine Crispen is used to being mistaken for her boss, but is Nancy Reagan used to being mistaken for Elaine Crispen?

"I've noticed that," Mrs. Reagan said when somebody asked her about it the other day.

Crispen's arrival at Bangkok's Grand Palace set off a flurry of activity among the Thai media.

As the Bangkok Post reported the next morning: "About the same height, the same colour of hair and the same hairstyle. From afar, anyone could have been fooled, and many of the photographers had their cameras clicking away."

A similar thing happened on the Reagans' 1983 trip to Japan, when Crispen was a special assistant. Then press secretary Sheila Tate explained to Japanese reporters that the woman they mistook for Mrs. Reagan was Crispen.

It was difficult to tell, a Japanese reporter replied, since "You Americans all look alike to us."

The Nancy Reagan orchid Indonesia's Hartinah Suharto gave Mrs. Reagan in Bali went right into her compartment aboard the Air Force 707 that flew her from Bali to Kuala Lumpur, Bangkok and Tokyo.

Yesterday, Dendrobium Nancy Reagan, hybrid of Dendrobium Norma Jackson and Dendrobium Michael Sado, was home at last -- at the White House.

Talking about it to reporters traveling with her last week, Mrs. Reagan said she was pretty sure she could find a place in the White House where she could fit it in, and that she'd never heard of an orchid with a family tree.

"I'm pretty impressed, I'll tell you."

She wasn't nearly so impressed with a question about whether U.S. Department of Agriculture restrictions on live plants coming into the United States might affect Dendrobium Nancy Reagan.

"I don't know," she said, sounding a little annoyed. "I guess if they can't, they'll go through whatever they have to go through." She rejected a suggestion that her case could be an exception, saying, "No, I don't want them to make an exception. If I have to go to jail, I'll expect you all to come and visit me."