How much are they charging for the silver u/Judedadude998? Your first step is to have the pawn shop owner set them aside, second step is to put down a deposit so they know you're serious (get a written receipt for proof of this). I'm willing to contribute for the deposit so you can get your precious memories back. Once you turn 18, cut them out and never look back. They see you as nothing more than a paycheck.

Also I highly recommend considering reporting the coins as stolen to the police. They may or may not be able to help you recover the coins, but having the paper trail will help you when you go to leave and they try to keep you under their thumb. You gave them the coins under the assumption you would get them back; them not doing so makes this theft.