First appeared in Fantasy and Science Fiction. Reprinted by Groff Conklin, Terry Carr, Robert Weinberg, Stefan Dziemianowicz, Martin H. Greenberg, and John Gregory Betancourt.
At a government building, the protagonist runs into a trio of aliens in slouch hats. He picks up a coin and insinuate that the space program has been more successful than he thought.
While minor, this story might gain more power rubbed against "Mimic", his best story, which also had beings in slouch hats. You'd get a darker flavored Men in Black.