Offically, the machines need US quarters; however, if your coin is the right size and weight, it might take it. (Also called slugs) Most coin operated machines use size (determined by the slot you insert it into) and weight (interally done) to determine that it is the right coin. However,more and more machines now use high tech features and will not only not give you what you want, it will keep your slug.
Having said that, it is a federal crime to use "slugs" in place of legal US tender. (Thanks Mr. Humbug)