U.S. growers produce nearly $35 billion worth of marijuana annually, making the illegal drug the country's largest cash crop, bigger than corn and wheat combined, an advocate of medical marijuana use said in a study released on Monday. The report, conducted by Jon Gettman, a public policy analyst and former head of the National Organization for the Reform of Marijuana Laws, also concluded that five U.S. states produce more than $1 billion worth of marijuana apiece: California, Tennessee, Kentucky, Hawaii and Washington. California's production alone was about $13.8 billion, according to Gettman, who waged an unsuccessful six-year legal battle to...