Magic mushrooms. Magic mushrooms is the name given to the mushroom psilocybe group. These mushrooms when eaten can cause hallucinogenic episodes along with nause and vomiting etc. The danger is not stunting of growth but rather of using drugs that alter the mind, and then what does that lead to later. More powerful drugs? Behavior problems, school problems etc?
It's not known. Why? Are you "volunteering" to be a subject in a study? There would be no real way to prove this one way or another. To do so, one would need a sample of people who consumed psyllocybin mushrooms, and a matched group which didn't, and then track them as they matured. There would be too many other variables to control, and the "subjects" would tend to get "lost" to follow-up.