Fresh
Psilocybin mushrooms are naturally occurring — they either grow out of the ground or are cultivated from mycelium spores. Different strains of psilocybin mushrooms grow naturally all over the world and some people have been known to forage for them.
Picking these mushrooms yourself, however, can be dangerous. There are over 10,000 species of known mushroom, some of which are poisonous to humans. Without knowledge of the different types, species and dangers of various fungi, it can be easy to confuse one mushroom with another and pick one which will leave you comatosed, as opposed to one which will give you a psychedelic trip.
Dried
Mushrooms are composed of around 90% water and so when dried they lose around 90% of their mass. This means that the same dose of magic mushrooms in a dried form will be around 10x lower in weight than a fresh dose.
If the moisture isn’t extracted from mushrooms when they’re picked they can rot fairly quickly, which destroys not only the mushroom itself but also the psilocybin contained within. Eating rotten magic mushrooms is never a good idea — the mould will cause severe stomach issues without any kind of psychedelic experience.
The market for magic mushrooms is illicit and unregulated as psilocybin mushrooms are illegal in almost every country. The danger of purchasing any kind of magic mushrooms (fresh or dried) is that, unless you’re an expert, you will not know exactly which strain you’re purchasing.
There are many different types of psilocybe mushrooms and some are stronger than others. Consuming a dose you believe to be a weak strain may bring about unexpected and unpleasant effects if turns out to be a different or a stronger variety.
Powder
Magic mushrooms can also come in powdered form; sold as capsules or as the powder itself. The dangers of purchasing/receiving psilocybin in this form are greater than the fresh or dried variety. It is far easier to add adulterants to powder which greatly increases the dangers of substances of unknown origin, quality and quantity being mixed into what you believe is pure psilocybin powder.