Your chance of finding a dollar coin made of silver from a bank are vanishingly small. Ike dollars were only produced in 40% silver as not for circulation coins that were sold directly to the public at a premium. These very rarely end up in rolls, though of course you will read about the time or two they have been found. However, you won't read about the millions of trips folks have made to look for them when no silver has been found. Buy a copy of the Red Book, it has tons of useful information.