Unfortunately my local gas/beer station doesn’t seem to take junk silver.
That's what they don't tell you.
You buy junk silver with dollars and you sell junk silver with dollars.
It's not money - it's a commodity - one with only maintains it's current value due to a group of people who think it has some inherent worth.
Great Britain used to use pieces of wood for their currency (tally sticks). Nothing special about gold or silver in a monetary way.