Yes, bamboo socks. There are a lot of new and old cool natural fibers out there that are still crowded out by the cotton lobbies and what not. But as we explore alternatives to the oh-so-last century petroleum based nylons and polyesters (please, people, make some better gym shorts!) we find that many of these fibers are more drought tolerant than our beloved cotton, organic or not, can be grown in poorer soil, and thus require far less water, chemical pesticides and fertilizers. These fibers tolerate broader weather imbalances and many of them grow fast. And, not unimportant either, they are natural and comfortable to wear. I had no clue that you could make fiber out of bamboo until I found these socks, which are incredibly soft and comfortable to wear. Although I later learned that the process is not so eco-friendly compared to some other natural fibers out there.
Better alternative fibers are hemp (poo pooed for years because of the supposed marijuana connection - but it is a non-psychoactive member of the cannabis family), which is drought tolerant and easy to grow, as is flax (currently mostly grown for its omega-3 rich seeds). Lyocell or its tradename Tencel, which doesn't sound very natural and has its detractors because it goes undergoes a lengthy industrial process, is a fiber made from eucalyptus trees. Something really exotic is SeaCell fiber made from cellulose and seaweed (mmh, maybe better to eat the seaweed), and also SoySilk, made from the leftovers of the tofu industry (now that's a good one, what with all the tofu we now eat).
So many new fibers made from natural materials to explore.