I had the exact same problem a few weeks ago, and no matter where I turned I couldn't figure out how to do it. I wanted to make a BG with a path running through it. After weeks of frustration I decided to go back to basics.
I drew pages and pages of grass. Individual blades up close and large bunches of grass, all in different shapes, sizes and distances. Then I drew rocky path portions, and tree bark, different plants, stars, the moon. I drew everything my picture was going to be composed of.
Then I googled for picture references on how paths wind through grass. Finally I decided to slowly and carefully draw out my background, and it's now in pencil form and I'm very satisfied with it.
Good luck!