Looks like a 'struck through grease' error? Like the steel penny? The 0 in 1990 is partially faded. Also is there something wrong with the rim it looks to be thicker on the right side? Sorry the pictures are not great...
I agree. It looks like a minor minting error. Value is low.
In addition to 'struck through' error, it looks like the start of an 'offset' error as well. See:
Paul Richards Ok. Thank you! I appreciate this website!!