Peyote is a small, button shaped cactus native to Mexico and southern parts of the United States. Potent compounds in peyote, such as mescaline, cause it to have a hallucinogenic effect in humans.

In the fall of 2012, I set off from my apartment in Mexico City and traveled nine hours through rough terrain to the Chihuahuan Desert to illegally dig up and take peyote. Growing up in Connecticut, I ...