To most Americans, an accent is something that only other people have, those other people usually being in New York, Boston, and the South. And of those other people, half of the ones you meet will swear they "don't have an accent."
Well, strictly speaking, the only way to not have an accent is to not speak. If you're from anywhere in the USA you have an accent (which may or may not be the accent of the place you're from). Go through this short quiz and you'll find out just which accent that is.