I was looking through my postcard covers and this caught my eye. I thought it was just another mis-cut Franklin stamp, but upon closer magnification, it looks like another stamp entirely.

It's got a little wheel shape on the left, and the text looks like it reads: "[Washington?] Bureau Engraving?"
What is that?
I was just reading about this very issue in the Max Johl book, where it discusses all the various plates and engraving errors.