What you have are a set of normally-oriented, incuse letters. There are two possible culprits: 1. The coin was struck through a very thin piece of metal that had previously been struck against a planchet, causing the metal to mold itself to the recesses of the die face. The metal flake became dislodged and was struck into the planchet represented by your coin. 2. A very thin flake of metal detached from a newly-struck coin, remained behind in the striking chamber, and was struck into the planchet represented by your coin. In either case, it's a relatively rare type of error.
It's probably worth $50 - $75. Not worth getting graded. If graded, there's no telling what sort of label will be affixed to the slab. The most optimistic outcome is "struck through struck fragment". But you might get a completely inaccurate or incomplete description like "struck thru", which won't help at all.
You can get a very similar effect when a large, multi-element dropped filling is struck into a coin. But the well-defined margins of the struck-thru area, and the faint suggestion of striations would most likely eliminate that possibility.
I was wondering what year it was? Looks like a copper cent? i think the lamination (Mike Diamond) could have not bonded. but, Also looks like a clash. But, because the E Pluribus is Doubled I would call it a Counter Clash.
Very cool error that seems to promote discussion whenever it comes up. Awesome find! Here's mine: https://www.cointalk.com/threads/ebay-pick-up.196214/