I've never personally heard any stories of "contaminated mushrooms". But there are other similar risks - like mistaking poisonous mushrooms for magic mushrooms

I've never personally heard any stories of "contaminated mushrooms". But there are other similar risks - like mistaking poisonous mushrooms for magic mushrooms. In general, magic mushrooms are either cultivated indoors by someone in a terrarium and keeping the environment just right. To even grow the mushrooms (which are fairly weak compared to most other fungi and bacteria) you actually need to start by sterilizing the substrate, usually by boiling, then you inoculate with a sterile needle the spores. Overall, this is pretty safe because pretty much any kind of contamination, the fungi won't fruit (you eat the fruiting bodies), so there's just not really any mushrooms to give you. The other way is of course to go mushroom hunting. This is a lot more dangerous, because there are mushrooms that are poisonous that will straight up kill you. It can be hard to tell the difference sometimes, especially if you don't know what you're looking for. One last thing is your body already kind of knows they are a toxin. Many people feel ill or sick to their stomach after ingesting them, and some will throw up. In terms of drug safety, eating things is probably one of the safest, because your body is always ready to expel bad food. The least safe of course is probably straight injection, and smoking isn't too great for you either. I won't say they're safe, but what really is in this world?