My sister uses organic dyes to overdye her wool for her hooked rugs. She's so good at it, her wool is sold at several LQS around Ohio to use in quilts, rugs, felting, etc. She buys her wool fabric by the bolt. Some are light color tweeds, stripes, plaids, light color solids, etc. She boils the wool, then dyes it. She has made some beautiful fabric. She's used walnut husks, onion skins, bark, etc. to make some of her dyes.