One of the niftier organic fibers I've seen is undyed cotton that is naturally soft orange or green. Inua Wool Shop hereabouts has it. Cotton is one of the nastier crops for the environment, with tremendous amounts of pesticides used to grow it. The pesticide-resistant varieties have actually made way for new pests, because the pesticides were too specific to the boll weevil. So organic cotton makes a tremendous difference in the health of the land. According to the Organic Cotton Directory, cotton provides half of all the fiber in the world. So going organic in your clothing will make a significant dent in the poison load of the world.
There's an interesting article on the resurgence of color cotton and organic cotton and breeding at the Organic Consumers Association website.