I have always thought that the Green River Whiskey piece was a bottle hanger - the manufacturer hung the token on a string or wire around the neck of the whiskey bottle. Since things like this are seldom thrown away, they figured it would be carried around as a pocket piece. The company would get advertisement value out of the piece for years. There is a Willow Calf Shoe piece that was used similarly, only it was tied to the laces of a new pair of shoes.
Others have theorized that the Green River piece was given out by the whiskey distributor and was good for a shot of the stuff at a bar that carried it. Another advertising scheme, but since most (if not all) are holed, I think the bottle hanger theory is better.
John in ID