plating disturbance forehead. Strike through memorial. Thought I seen the words "pluribus unum" and i lost it. Now I don't know!
The issue on the Reverse is a Lamination of the Cupro-Nickel. By the way.. Nickels are not plated. The rest of what you see is corrosion.
It is worth 5 Cents.. They don't grade or attribute damaged coins. The Lamination is cool but not really a major issue. Waste of money if you send it in. They don't refund you for damage.
I would rather burst your bubble than give you false information and false hope. You are welcome.. Don't worry in time you will understand better what true errors are. Try to first find out how coins are minted. Then you will see why certain things cannot occur during that proccess. Damage is easier to understand then.
Curiosity is good. Somebody has used a lettered punch to impress that word on the back. In the 1800's to the early 1900's business owners 'counterstamped' their name or business on it to make it a spendable advertising token. In the 1920's speakeasy owners would counterstamp a coin to be used as a pass. It was not too popular in the later 20th or in the 21st century. Your coin may have been counterstamped by a club or organization to use as a proof of membership. If you can make out the word(s) you might try to find out more. Even nearly perfect modern coins wouldn't be worth much and any marks would make it worth less. Yours is worth a nickel if the bank will take it. But, if you do some research and put it in a time capsule it might be worth something for somebody far in the future.