Wide receiver Percy Harvin collapsed on the field at the Minnesota Vikings' practice Thursday and was taken to a hospital in an ambulance, according to reports. Harvin has suffered from severe migraine headaches since childhood. According to the Minneapolis Star Tribune, Harvin suffered a migraine earlier Thursday. "I don't know how to classify" the episode, Vikings Coach Brad Childress said, according to the Star Tribune. "Not really a seizure, but he had some trouble over here. I'd be remiss if I tried to qualify it one way or the other. He seemed like he was stable. Shugs [head athletic trainer...