Ah yes, organic dyes.<p>My wife specializes in this area with her fiberwork. I've picked up a few things.<p>You can also use: onion skins, avocado pits, ironwood, oak galls, copper, iron, and plenty more. It's awesome looking at some of her historic dyework books, realizing just how many reactions are going on per batch. And indigo - real indigo leaves and fermentation is just an absolute beauty to watch. The vat isn't deep blue - but turns that way when oxidized in air.