Yup. The Super Mushroom is real. Sorta. That's the Amanita muscaria, commonly called "fly mushroom," that's found in Northern Europe and Scandavia. Eating it won't cause abnormal growth, but hallucinations or even death. With the way some people are, I'm just surprised some moron hasn't gotten sick eating one of these and then blamed it on Nintendo! So, remember kids, don't ingest things you find in the forest. Words to live by!
Super Mushroom [Gigazine via Tokyo Mango]