I teach a botany class in our home school co op, and I'm doing a lesson on vegetable dyes. Since Easter is coming up, it would be fun to dye white eggs rather than fabric scraps. What types of plants have you tried for this, and what do I need to add to help the color stick to the shells? I am thinking pomegranate, oak bark, black tea, purple cabbage, carrots, steeped in boiling water with Tb of white vinegar. I usually do vinegar plus food coloring with good results, but never tried plant dyes on anything. Anyone tried this? tia!