The classic example of this is the "O.K. Vender" slot machines, made by Mills between about 1910 and 1932. Smith and Alpert list 80 varieties of "O.K. Vender" tokens, and there are probably more that have not been cataloged. Smith and Alpert quote a 1913 Mills catalog description of this slot machine:
A package of gum (Bell Gum Fruit) is delivered for every nickel deposited - legal tender for value received. In addition the machine, at certain intervals pays profit-sharing dividends of from 2 to 20 merchandise checks [tokens]. When one of these dividends is to be paid, the fact is announced beforehand in the window on the front of the machine. The player, therefore, knows in advance exactly what he will receive. At his option he may take it or leave it. There is absolutely no gamble or chance.The "O.K." part of the name is in reference to the fact that these were supposedly not gambling devices, and thus were "O.K." (the 1913 catalog devoted several pages to assuring their legality, and quoting court cases). Be that as it may, most people played them like slot machines, not even bothering to remove the gum, which was low quality and probably worth less than a cent.
Here is a selection of O.K. Vender tokens: