The goal of this clinical trial is to test psilocybin in combination with mindfulness training in healthy adults. The main question it aims to answer is "Does mindfulness training enhance the effects of psychedelic therapy (psilocybin) on mental health?" Interested individuals will complete an initial eligibility session and eligible participants will then be randomized into one of two groups: one dose of psilocybin (administered under the supervision of study therapists) combined with 8 weeks of weekly mindfulness training classes (Arm 1) or psilocybin alone (Arm 2). Both groups will complete baseline and post-treatment assessment sessions where they will complete questionnaires, computerized cognitive tests, and have an EEG (a measure of electrical activity in the brain). Both groups will also complete 2 follow-up surveys (at 8 weeks and 1 year after the post-treatment assessment) either online through REDCap or by phone or video call with a research assistant.