This was a couple years ago now, but I had sex on mushrooms once and it was the most bizarre sex I've ever had. Not bad at all, but I couldn't say it was particularly ... good, either? The most interesting thing was that I couldn't figure out where my body ended and my partners began - it was this strange, "gooey" sort of melting of one body into the next. I don't even really remember how we started having sex and we didn't particularly "finish", either ... we just sort of rolled off one another and continued cuddling and looking at the ceiling.
So if you're trying to melt together into a weird, naked pile of goo, go for shrooms ... otherwise maybe try something else, haha.