Meet a genuine American folk hero cut from the homespun cloth of America's heartland: Sam Walton, who parlayed a single dime store in a hardscrabble cotton town into Wal-Mart, the largest retailer in the world.  The undisputed merchant king of the late twentieth century, Sam never lost the common touch.  Here, finally, inimitable words.  Genuinely modest, but always sure if his ambitions and achievements.  Sam shares his thinking in a candid, straight-from-the-shoulder style. In a story rich with anecdotes and the 'rules of the road' of…