 The report from the RAND Corporation estimates that about 3% of adults tried psilocybin last year, making it the most popular psychedelic. The runner-up was MDMA, or ecstasy, at just over 1%, followed closely by LSD. Half of people who took mushrooms said they chose to microdose. Dr. Joshua Woolley, a researcher at UCSF, says microdosing is increasingly popular, but much of the evidence on psychedelics is based on people taking much larger doses while also receiving therapeutic support.