Errors on gaming tokens made by Franklin Mint are very rare; they had great quality control. However, this one got by their inspectors. The token is the big $5 1967 sterling sliver (.925 fine) slot token made for Riverside in Reno.

The error is called a "Partial Collar". Here is Coin World's explanation of how this happens:

Partial collar: Often known as "railroad rim" errors, the edge, not the rim, is the portion of the coin affected. It occurs when the collar is pushed somewhat below the surface of the lower die, so that the upper portion of the coin is free to expand beyond the confines of the collar, while the lower portion is restrained. On coins struck from a reeded collar, partial reeding exists on the area restrained by the collar. The error gets the nickname "railroad rim" from its appearance - the coin, viewed edge-on, resembles the wheel from a railroad car.

This one is for sale if you collect token errors. The token is Proof-like and in all other aspects a near perfect token. Price is $100, delivered.