If you are picking it's VERY important to have somebody who knows what they are doing at first. Poisonous mushrooms are really nasty, and you don't even know you are dying until it's too late, without an immediate liver transplant. And the chances of that are practically zero. The stems tend to turn blue after you pick them, which is a sign psilocybin is present. Drug test kits can tell you that, too. I don't think there are any poisonous mushroom species that contain psilocybin, though some are notorious for being nasty for your stomach.
Purists insist on fresh mushrooms, but it is really easy to extract the drug with alcohol. You just powder dried mushrooms, soak then for a few days in 191-proof ethanol or concentrated isopropanol. Then filter and collect the alcohol, and evaporate it. You can put the resulting dry powder in caps or even smoke it! No stomach upset, no nasty taste, just smooth sailing. Great for listening to music and sex, too.
If you are really industrious, you could capture the evaporating alcohol in a distillation setup and reuse it for the next time.