There are lots of American grownups going around buying toys as collectibles - and as playthings.

Men and women from all walks of life are picking up teddy bears, jacks, toy soldiers and rubber ducks, according to an article in the current issue of Harper's Bazaar. Some collect old trinkets; others buy them new and without embarrassment at their seemingly juvenile predilictions."Seventy-five to 80 percent of our customers are adults buying toys for other adults," said Gregory McMeekin, vice president of the Last Wound-Up toy emporium in New York City.

One high profile collector is Malcolm Forbes, whose Fifth Avenue gallery features hundreds of bathtub-worthy boats and inch-high soldiers among his jeweled Faberge eggs, original presidential papers and paintings by Rubens, Van Gogh and Renoir.

"I used my children as a front to begin collecting," admitted Forbes, the father of five, whose habit started some 25 years ago at an antiques auction. A consignment of World War I doughboys was on the block.

"The minute I saw them, I was flooded with recollections of the hours my four brothers and I spent parading and knocking down each other's troops and my hand shot up," Forbes said. "For better or worse, it hasn't been lowered since."

Rarity and monetary value are not the sole reasons grown-ups crave toys. Nostalgia is a major factor, too.