1999 American New Jersey quarter with a large bump or swell on it

This is an unusual coin defect that has me wondering if it could be possible-even when I'm holding it in my hand. Everything about this quarter is normal except for the fact that George Washington has quite a large bump on his head. I'd like to know if this is for real, and about how many of these quarters were made with this defect. I'd also like to know if it has any significant monetary value. The front of the quarter is the only side affected- the back shows the normal New Jersey state scene. I'll try to get some better photos if necessary. Thanks for any help and take care!