There is the one that appears on most of his cards, then the Saturday Evening Post stamp that uses his first name, but still has the same address (I've only seen that on the one card), then this shows up on eBay overnight ...
http://www.ebay.com/itm/T206-Jake-St...item565e27794e
Looking at it one way, the person's initials are WH. But if stamped from the other side, it becomes HM, and it is on an Old Mill back, which he stamped plenty of. Hummmmm, should I bid or pass?