RecruitingPhase 1Drug trialPsilocybin in Chronic Low Back Pain and DepressionThis study seeks to provide insight on psilocybin's effects on mechanisms of chronic pain among patients with co-morbid chronic low back pain and depression (CLBP+D). Participants will receive either a single high-dose of psilocybin (25mg absolute dose) or methylphenidate (40mg absolute dose). Participants will be asked to complete assessments of pain, depressive symptoms, and more general questionnaires regarding the participants experiences during the experimental sessions and the associated enduring effects.