Franklin Mint made the great majority of gaming tokens for Nevada casinos from 1965 throught 1969. This includes the tokens played in the casinos as well as sets of proof and proof-like tokens for collectors. Many of those sets have been broken up and sold individually; that's probably what you have.

The 1967 sets had many $5 sterling silver tokens that were removed and melted in the 70's when silver was high priced. That's why you see more dollar tokens with that date in pristine condition as they were the leftovers (no silver content). Most of these sell for $3-5, although tokens from the better known casinos often bring much more on eBay.