My friend had this coin and said it could potentially be worth some money because of the no S mint mark. I don' know too much about this type of stuff and would love to know if it is or not
Philadelphia. No mint mark in those days. It's worth a dime. The 1968-S dimes are proofs and they look a lot nicer than regular dimes.
First, welcome to the neighborhood! Please tell your friend that there are some "No S" coins from various years that are worth money, but they are proof coins. Proof coins are struck on specially prepared planchets by highly- polished dies which produces a mirrored finish in the fields. Also, please tell your friend not to believe everything he reads on FleaBay or BoobTube. Chris