 McMahon used the government Cannabis to treat pain, spasms and nausea related to repeated injuries, surgical and pharmaceutical maltreatment, and a rare genetic condition called Nail Patella Syndrome, which causes bone deformities, immune system dysfunction, and a propensity for renal failure.During the authoring of "Prescription Pot", Largen traveled the United States with McMahon, documenting the latter's efforts to educate doctors and legislators about the therapeutic value of the Cannabis plant.The book details one of their journeys through Texas, to the Arkansas State capitol building in Little Rock, to Elvis Presley's Graceland, culminating in their arrival at the University of Mississippi, where the U.S. Government grows marijuana for the federal cannabis program.