Here's a website I found helpful in explaining the various types of eco-paper, This Company being 1 of the Top 4 Leaders for "Tree-Free" Papers. I don't know how current this site is, but appears up to date.
Wood-Free is not necessarily "Tree-Free" from what I've read.
And yes they even mention Elephant Dung or "Poo-Paper" which evidently there's a substantial market for.