fly, first, welcome to the forum! You'll enjoy it here with lots of friendly people and a knowledge base which defies description.
The coins to which you refer are actually souvenir tokens rather than spendable money although in some towns or cities which produce them for special occasions often will accept them in lieu of actual cash payments. (I'm not certain if this practice is strictly legal in the US, but I've seen it done on many occasions. It might be considered "barter" instead of actual cash, but I've never heard of the US Dept of Treasury ever complaining.).
The tokens themselves have no intrinsic value except to those who collect them or who collect souvenirs of those sites where they visited. They cannot be spent at anyplace other than wherever they were sold, if they could be spent at all.
Lake Havasu isn't that far from where I live here in Arizona, but I've only passed through the place rather than actually stop there to visit. It's too much of a tourist trap although I wouldn't mind obtaining a couple of the souvenir "dollars" since I have a casual collection of such tokens (largely wooden nickels, some "Maui dollars" and other good luck pieces or bar tokens).