Hemp is the most efficient material for socks: it’s durable, it breathes better than all other plant fibers and it’s more resistant to bacteria than cotton. It’s also grown a environmentally sound manner without pesticides. All of these factors give it the edge in terms of sock efficiency. Usually, the hemp fiber is blended with cotton and spandex for support.
See also these hemp socks by Brothers Organic: men’s and women’s versions available from Good Humans. The women’s version is 42% hemp and 58% flax (soft but may not stay up), the men’s version is 74% cotton, 25% hemp and 1% spandex.
Rawganic also has some hemp socks available.