Use the head of the cabbage to produce gorgeous lilac purples or blue-greys. Also, the outer leaves of the cabbage (which you'll have access to if you grow your own cabbage or intern on a farm!) produce the most beautiful soft greens.
Berries, Natural Dyes by Philosopher Queen. This was my first job with CW between college years: we built a fire, boiled some berries or leaves and dyed some wool spun by CW's Spinning and Weaving Shop.