S pennies what are they?

If, by "S pennies", you mean that the pennies have a small "S" on them near the mint year, that means that the penny was minted in San Francisco.

I think pennies are not being minted there currently, and even when they were, fewer pennies were made there than at the two "main" mints in Philadelphia (no mint mark on pennies, "P" on most other coins) or Denver ("D" mark) so an old "S" penny in good condition may be slightly more valuable than another penny, although probably not by much, it would have to be in first-rate condition and decades old to be worth more than a buck or two. A few rare dates are worth more.