It looks like some ink was transferred from another bill. I had a similar one where Washington DC was transferred, (mirror image of course), i sold it on ebay. It has a slight premium, maybe a couple of bucks.
That is a Series 2006 note and it appears that when it was received (fresh) it was folded by someone to present a mirror image of the folded area. Look at the crease lines near the seal and running through it. While it was folded it very well could have been rolled with a small hard round object...this might account for the blur in the seal image...anyhow, just a guess on my part. But I agree with the other post as well. RickieB
well it is kinda neat, but it is only worth $1, and any collector in the future will quickly find out how the damage was made. And since it is post printing damage, i doubt it would ever fetch a premium.