Dr. Sunil Aggarwal says he has a right to prescribe psilocybin — the hallucinogenic compound in “magic mushrooms” — under state and federal “right to try” laws, which give terminal patients access to experimental drug therapies before they are approved by the U.S. Food and Drug Administration. More than 40 states, including Washington and California, have such laws in place, and Congress passed a federal version in 2018.