Heres an interesting one.
Purchased this cover yesterday because of the YMCA labels on the back. Postmarked in Tacoma WA in 1918 with 3 1¢ Washingtons.
It's in sad shape, but still quite lovely. The paper resembles wood, and the image on the front is hand painted in what looks like india ink.
But the kicker was the date on the postmark. November 11, 1918. The LAST DAY OF WWI!
Here's a history of Camp Lewis.http://www.historylink.org/File/8455