I was bad. I picked these yellow flowers from a local park. I know it's not a good idea to pick flowers that are there for everyone's enjoyment, but, it is late fall and they won't be lasting too much longer, and, I only picked a few flowers from each plant (to minimize their absence).
And, I was bad, because I used these plants and I have no idea what they are! I should make some attempt to figure out their name. I've seen them around different areas, like a weed. The plants grow to about 30" high, and are about 24" across a clump. I didn't notice until I started to pick them that they have a very sticky 'sap' on them. It's on the flower petals and the receptacle. I picked the whole flower, and then when I got home, I separated the yellow petals from the green receptacles.
I made up three dye baths. One for the green and yellowish receptacles, one for the yellow petals and another using onion skin from a yellow onion. I left the fabrics in the dye baths for about three days.
Here are the results:
Left, the weed's receptacles, middle is the yellow petals, and right is the yellow onion skins.
I really like the unexpected variations of color from the receptacles.