coin roll hunting. And it's exactly what it sounds like: searching through rolls of coins to hunt for collectible and valuable coinage.
The main thing most hunters are looking for are old 90% silver coins. Those would be pre-1965 U.S. quarters, dimes, and half-dollars. They also search for 40% silver U.S. half-dollars (1965–1970) and 35% silver war nickels (1942–1945).
Older coin designs, like the wheat penny (1909–1958) and buffalo nickels (1913–1938) are also hunted and collected.
On top of that, coin roll hunters look for proof coins that normally wouldn't make it into circulation, toned (colored) coins that catch the eye, and coin varieties and errors.