I've had luck with a flowerpot.
IMO, coral wise, toadstool leather is best.
I prefer them LPS as they won't retract into their skeleton at night, the clownfish might scratch their body against the skeleton, and they also don't have powerful sting. For larger mushrooms, they'll also shrink at night and the clownfish might scratch their body against the rock.
If you get a nice specimen like green or yellow they can look pretty striking.