This is actually a leather postcard my grandmother sent to her cousin, "Miss" Lillian Yardley, who for some reason was in John C. Proctor Hospital in Peoria, Illinois. See the "I.J.J." in the lower right corner? Sound like a radical labor union? Those are the g-ma's initials: Ida Josephine Jones. The card is postmarked October 4, 1907.
Update II: Just for the hell of it I googled (lousy commies) for "leather greeting cards," thinking there must be a thriving trade in them, but all I found were "adult" cards and this. Must be doing something wrong.
Update III: I was. Even though the back of the card clearly says "Post Card," I googled "greeting card." There are tons of leather post cards around. They even seem to be something of a drug on the market.