IIRC, pre 1965 quarters were 90% silver, 10% copper and pre 1971 half dollars 60/40. like I said, everyone seems to be doing it these days. If you get a roll that came from the Treasury, via the bank you'll have about a 0% chance of finding any silver. Customer rolled, I've heard people getting $4-$5 face value, recently. Those hauls seem to be getter fewer and farrer between, though.
I have a tale from when I was a kid working the register at a burger place back in about 1975. I opened a roll of dimes, and every single one of them were from the 1910's to the '1940's. Opened another one. The same., Another the same. Ended up buying all the dimes, and 90% of them were Mercury dimes, many in near uncirculated condition. (4 rolls) for $20. Not a bad investment for a 18 year old kid back in the day.