Quincy Mumford is a local guy, a Jersey kid, who picked up a guitar when he was in third grade and hasn’t put it down yet and although he is only 19, his sound, his performance, his mojo has something of a seasoned quality about it, a rock confidence that suggests a past in his presence and a significant future ahead. Along with his band The Reason Why, Mumford plays all over his home county of Monmouth, including a monthly gig at Jamian’s in Red Bank. They also have dates all over the U.S., including an upcoming show in St. Louis at the NCAA National Convention. And Mumford recently shared…