Alcohol. Though with the side-effects, potential for life-long addiction, etc. - I really do not recommend doing that.

Travel to Oregon or any of the various places these things are legal.

Or produce the necessary items on your own. Growing things isn't difficult.

Step 1 is to get rid of the idea that some people are "criminals" who you shouldn't be interacting with. Over half of Americans have used illicit drugs.

Chances are, someone you already know can hook you up with psychedelics. Try talking to your best friend about it. If he doesn't know, try another friend. You won't need to ask a third friend.