This is a Macah-Nootka, Northwest coast Native American lidded basket, among my very favorite baskets in the world. Here with what I believe are black ducks marching (rather than swimming) around the perimeter--and specifically red headed ducks, the color on their heads faded over time, but visible as bright red on the interior. This one is unusual for the plaiting at the center of the lid (in addition to the plaiting on the bottom, which is common, though variant; here I believe raffia rather than cedar bark, which helps to date it.) In searching I can find a few examples of plaited lids out there, but I'd never come across one like this before, and with a nice dark, mossy green wave-like border around it, too.

 4 1/2" w x 3" d x 2 3/16" t. I believe 1920s-30s or so, with the grass aged a nice warm honey color. Some minor irregularity/slumping to the form around the recessed lip but the lid fits over it just fine.