Earlier this spring I took one of the nicer seiryu stones from a previous scape and planted an oak sapling around it out of boredom. The oak died soon after, but I took a maple seed from a neighbors tree and stuck it in the little bit of dirt that was around the rock (wrapped in cellophane).
To my surprise the maple sprouted and it now a good 8 inches tall. I'll give it a couple of years before removing the plastic wrap/ twine and washing away the tiny amount of dirt. Hopefully it will turn out okay considering I haven't been able to arrange the roots around the rock in any way haha.