I'm not really interested in the natural dyeing movement, but I saw a blog by Jennifer Coyne Qudeen here
http://jennifercoynequdeen.blogspot.com/2012/06/art-math-answers.html, and decided to try it out.
I bought some roses at the grocery store,
and added some rusted nails and washers, wrapped it up tight,
and plopped it in the crock pot for about 6 hours. It smelled wonderful, and I got this great piece of fabric out of it. Here's a closeup.
I tried this with a white t-shirt from the Gap, but I think I over crocked it, I left it in for 16 hours and got lots of grays and black. not worth posting.