Post Office Department souvenir sheet.
<a href="https://en.wikipedia.org/wiki/United_States_Post_Office_Department" class="extiw" title="en:United States Post Office Department">US Post Office Department</a> <br> scan by <a rel="nofollow" class="external text" href="https://www.flickr.com/people/51764518@N02">Joe Haupt</a> from USA
<a rel="nofollow" class="external text" href="https://www.flickr.com/photos/51764518@N02/15216357096/">Philatelic Truck Souvenir Sheet, Mint Condition, No Gum, Issued By The U.S. Post Office Department, Circa 1939 - 1941</a>