 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 a 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.