My grandmother has been looking for a poem for ages, and in searching for it I stumbled across this forum and thought I'd give it a try.
She remembers the basic plot, which is that a young soldier is going off to war (the Civil War?) and leaving his girlfriend. When he leaves, the impression of the button on his uniform remains on her cheek.
I know it's not a lot to go on, but I figured it was worth a shot.