University of Mississippi lab is home to the nation 's only legal pot farm . The U.S. government grows marijuana , tests its potency . Like a cask in a wine cellar , this barrel of marijuana is marked with the year of vintage . Study finds percentage of psychoactive ingredient in pot on the rise . Score: 6
University of Mississippi lab is home to the nation 's only legal pot farm . The U.S. government grows marijuana , tests its potency . Study finds percentage of psychoactive ingredient in pot on the rise . Score: 6