I especially like the scan of the US flag cancels. The next to the last one (I believe 02/27/1898) in an oval from Boston, Mass. with a flag cancel looks to be one the scarcer varieties. Perhaps someone who knows more about them can chime in on that, but that one is a rather early example of a flag cancel.
Backing up to your first scan with cancel from Orient, Maine, I can't see a lot of detail to tell what die may have been used, but here's a recent link that shows some variations:
https://goscf.com/t/14268Although none are thought to be worth much monetarily, they certainly do make a nice display of "back of the book" material.