thanks to Alisa who found this one at Gypsy Hill Park duck pond. She says "I actually have no idea what they're trying to communicate to me with that message. " Me neither, Alisa.
maybe what they really mean is you can use other coins "only" if you call them "nickles."
(I'm jealous of Alisa for her experience which included unneccesary quotation marks AND ducks, two things of which I am very fond.)
14 hours ago