First, I would to say thank you for accepting me into the coin community forum. I recently inherited a few coins And as I was going through them and checking the values I realized a 2003 proof quarter has a different design then the normal 2003 quarter. Would this be considered an error because I've tried and I'm having trouble finding one like it. I've attached a picture, I'm a novice so I appreciate any help you can offer.
It looks like the coin you have is not a product of the US mint, but rather a privately struck coin. I found the following information about it. It's not much, but interesting. I would like to see a picture of the front of your coin as well. Thanks!