Oooh! I once pinned a page for this very thing...homemade concrete stains:
http://www.stainedfloor.com/
Maybe one of the copper ones for the leaves?
Your pieces are marvelous, btw. I will search, but might you give us a brief how-to? I really love the shape of your leaves and mushrooms.
Eta:
Yikes, retread your post. You got the acid stain already. There is a bit on that page I linked on acid. Not sure if your has color or not. Hope the page can help a little.
