In tall baskets among the produce aisles at Uwajimaya. OK, brown, but green...
600 5th Ave S, Seattle, WA
Saar's market at the corner of Rainier and Henderson has them. I suppose you mean unroasted unhulled peanuts. Green peanuts are unavailable, since the plant drives the seed pod underground before ripening, and green peanut pods are tiny.
They're a Southern Food, so if you live farther north you'd want to drive only to the Central District, since Seattle's highest population of Southerners is in its African American population.