I think this is a cut-out of an envelope. Probably from a set of stationary (writing paper & envelopes) sold to soldiers in the early 20th century. It's about 2 3/4" x 3 1/2". Ain't it cool?! Notice the small gun, an early revolver, in front of Uncle Sam's chips.

This one's a keeper. I already have it framed. The best part? Paid $1 at a flea market last week!

Please feel free to copy & use the image.