It's my best way of relaxing," says Princess Grace of Monaco of her "hobby that has become an occupation"—creating collages of flower petals, leaves and weeds. Grace braved the first exhibit of her work recently in the prestigious Drouant gallery in Paris. Some 50 collages were unveiled at an opening attended by a swarm of European glitterati, including Mrs. Valery Giscard d'Estaing, Mrs. Georges Pompidou, Helene Rochas and the Baroness Guy de Rothschild.

When she began to make the collages in 1971, Grace signed them GPK (for her maiden name, Grace Patricia Kelly), so that if they were a flop her husband and Monaco would not be embarrassed. The precaution was unnecessary. Rainier, whose hobby is blacksmithing, encouraged her to organize the Paris show and, as it turned out, all the collages(priced from $400 to $1,600) were snapped up. Profits went to her favorite charities, including a Monaco ballet school.

"Her work is not at all the work of an amateur," says gallery owner Danièle Drouant. For the past six years Grace has been collecting ingredients from the gardens and hillsides of Monaco, then pressing them between the pages of phone books. She worked secretly at the palace or in her Paris apartment, where she stowed the collages under the bed. Friends have helped out with exotic items from abroad, and on a recent trip to California she added some indigenous wild flowers, ordering the prince to pull over whenever she spotted a good specimen beside the road.

Would she have preferred art to processing? "No," she replies regally, "but I am a woman of action, which above all means being creative."