Our nation began 250 years ago with the Declaration of Independence. But this is a story about the nation's most important document, the Constitution of the United States.The Founding Fathers drafted the Constitution in 1787. However, a rare copy of the Constitution went missing until a man, who's now retired in Sierra Vista, stumbled across it."His eyes got wide and he said, 'Mike, I think we have something here,'" said Mike Munroe, recounting …