Well, the color that I was graced with by the Willow tree leaf is wonderful!
I love the fact that you can acquire a great yellow (all shades) from things growing in your backyard or side street. For this I just trimmed a few low branches from a huge Willow tree and clip them with scissors and simmered them up. When the plant matter sinks to the bottom of the pot (usually a few hours) you know that the dye stuff is ready to strain. I usually never have the patience to strain and I end up regretting it because I spend more time picking the particles off the wool - and that takes more time than straining. So learn from my mistakes!
The other color is from a weak bath of Black walnuts that have been sitting in a pot outside all winter. I did strain this one because the nut hulls just disintegrated when I heated this one up. I think it will make a lovely color for faces for my needle felted santas.
Here is a pot of Dandelion flowers that are just starting to sprinkle the lawns of the east. I can see already (soaking overnight) that it will also be a strong yellow. It's such a picture perfect pot with the blossoms floating.
For an end of year projects for my kids I hope to wash up a fleece that was just donated and dye with them. It will take a bit on my part to get it organized for a 40 minute class but maybe I will make a day of it and stay through recess.