Penicillin does come from fungus, but not Psilocybe mushrooms, as for whether it can grow on Psilocybe mushrooms, I'm not 100% sure so don't take my word for it but I don't believe it does. Maybe you could take a very very small (like 0.1-0.3g) dose first to check for an allergic reaction, and if you are fine then up your dose.