 There's a lot we don't know about the public's psychoactive preferences. But two new reports suggest that magic mushrooms containing the compound psilocybin are now the most popular choice. Let's start with the report from the nonpartisan RAND Corporation. That estimates about 3% of the public, approximately 8 million adults, used psilocybin last year. The fact that it was so much larger than LSD or MDMA, that was a bit of a surprise. Bo Kilmer with RAND says they surveyed about 4,000 adults.