As potent monsoon storms awaken a dormant desert around this time each year, Hernan Castro prepares to head for the southern Arizona mountains to forage for mushrooms that are a centerpiece of his life.

Castro’s passion for mushroom cultivation and ethical harvesting has earned him the nickname “mushroom man” in his hometown of Tucson. A self-trained mycology expert and regular fixture at farmers markets, he makes a living leading foraging trips to mushroom-rich places and selling fungi-related products through his online business, Desert Alchemist.

But this summer, Castro is not free to scour the landscape for fungi that thrive in moist environments and help sustain his livelihood. The lawful immigrant sits