Ive had one of them State Quarters collection that I've had for sometime. And decided to open the small bag of quarters. Well to my surprise I came across a 2000 P New Hampshire with an obvious error on the back. I would like to know where should I go to see what value it's worth and how to sell the coin?
That's a pretty good closeup but it is always helpful to post images of both the reverse and obverse of a coin. What was it that jumped out at you? If it's a secondary profile of the "face", that looks like Mechanical Doubling to me. It wouldn't increase the value even though it is neat looking to a new collector.