It's easy to grow your own (see the "Uncle Ben's Tek" on Reddit, see link below).

It is legal to purchase the spores and have them shipped across state lines in the US because the spores do not contain psilocybin. Somewhat fool-proof, takes very little space, can be done in under 2 months.

https://www.reddit.com/r/unclebens/comments/el1da3/part_1_ho...

It is legal in the US state of Oregon, and I think maybe one or two others I can't recall. You start by finding a doctor who specializes in the therapeutic use of psychedelics, and giving them a call! Watch How to Change your Mind by Michael Pollan.

Be safe, be smart, and consult a professional. I don't recommend doing it "street-style" where you buy it off the black market and take it at a rave :)

Legality varies. For the US, see https://en.m.wikipedia.org/wiki/Psilocybin_decriminalization...

But also, spores (which lack that chemical) are often legal, so if you want to avoid an illegal purchase, you could just get spores and grow your own.

Many other commenters have provided high-level background answering your question, but if you want to see how legalization/decriminalization is unfolding across the US, this is a detailed map: https://psychedelicalpha.com/data/psychedelic-laws

It's legal-ish is San Francisco and Oakland.