Dollar- Nice filled die error. It was probably struck through grease. This happens when the grease used for lubrication builds up on the die and fills a part of it. These errors are neat but rarely command a premium unless it's excessive or happens in such a way as to make for an interesting coin. One that immediately comes to mind were the Kansas State Quarters that had a filled first "T" of TRUST thus causing the coin to read, "In God We Rust."
