NESTING BASKETS (AFRICAN? NATIVE AMERICAN?)

FOUND AT AN ESTATE SALE. THE PERSON WHO OWNED THEM HAD A HOUSE FULL OF ANTIQUES AND COLLECTIBLES FROM AROUND THE WORLD. THE LARGE BASKET HAS SOMETHING WRITTEN IN PENCIL, BUT I CAN'T MAKE IT OUT. IT LOOKS LIKE "OPON"? ANY INFO WOULD BE GREATLY APPRECIATED! :)