Dandelion
My children loved this project. They harvested the dandelions and dandelion greens themselves. Here are the fruits of their labors simmering away in the dye pot.
The results!
On the left we have non mordanted wool treated with the dandelion bits dye. This yielded a disappointing, anemic light yellow. On the right we have wool which was treated with an alum mordant, dyed with dandelion bits dye, then modified with iron liquor. What a difference! A nice satisfying olive green.
Science experiment note: the two wool hanks were not dyed in the same dye lot. Since the first yellow was so disappointing, I had the kids gather about 25% more raw dyestuffs (dandelion bits) to see if it would yield a bolder yellow. It did not. So increasing dyestuff quantity is not a factor in making dandelion dye more aesthetically pleasing to my eye - mordanting and modifying was the answer. For me, I mean. YMMV:)