Who would do this and put it in circulation. I don't know the process on how the coins are made. It weighs 4.20 g.
PMD = DefDam = Definitely Damaged = Post Mint Damage : Looks like someone with extra time on their hands did that. It definitely did not leave the mint like that.
It has been ground down after it left the mint. You can see the grind marks. It is post mint damage. Someone could have been trying out a new grinder, maybe trying to make some sort of a trick coin. Who knows. The possibilities are endless.
You actually answered your own question, didn't you? Post anything you like. We're all eager to help out.
It's a 1999 or newer. That's when they started putting the dates on the reverse of the modern quarters. Worthless IMO. Go to the bank and maybe they will exchange it for a good quarter.
Maybe the beginnings of someone that was going to glue two coins together? Serious PMD. Is it now worth 12 ½ cents?
It's worthless because it most likely won't work in machines that accept coins, The coinstar, and if I was a cashier and I saw it, I wouldn't except it, nor would I give it to someone in their change back. Scrap metal if you ask me. That's why I would bring it to the bank and ask them for a valid replacement quarter. I knew a elderly woman who was a life-long golfer. She had a penny that was ground down on one side just like this quarter the OP posted. She used to use it to mark where her ball was on the green. Maybe that's what this quarter was damaged for. Who knows.