Picked this up recently in a box lot.
A sample "stamp" from a place that was intending on placing actual stamps on the sticker like an ad collar. The sticker would have advertising that would provide profit even selling the sticker with a stamp at a discount.
From what I could find out, they got all the way through testing with the post office, had some major customers, 7-11 as a seller, and big companies and the Post office as advertisers. Even had a press conference where they displayed covers from all 50 states.
Just after that the Justice dept squashed the idea. because attaching advertising to stamps wasn't allowed. The company was appealing that since they were attaching stamps to ads, not the other way around, pointing out that all advertising on envelopes would be disallowed following the logic of the ruling.
From the information included in the envelope, it seems the picked up Create America as a distributor, and they in turn were promoting it like a pyramid scheme. Stuff like "even if you can't use 500 stamps at 17 cents you can sell them to friends and neighbors for 18 cents" (Oh boy! a potential profit of $5!)
These are probably a second version, as the letter apologizes for the delay due to running out of sample stamps.

