According to the book i have only the proofs without the S mintmark were made accidentally, but it lists MS-65 regular circulation 1968 worth $1. Maybe my book is wrong though...
If it's a proof, it's worth a lot. If not, unless in top-notch condition, worth 10c Pictures would be great.
So you've found yourself a 1968 Philly dime. A lot of newer collectors are unaware that mintmarks for Philadelphia didn't show up until 1980. Finding a 1968 Roosevelt without a mintmark is not unusual and simply means it was produced at the Philadelphia (main) Mint.
