I agree that the stamp value is not very big ,but it is still a curious looking item. It resembles me a bit little to one of the expertised pieces of our Bulgarian expert Petko Karaivanov.
He was also a dealer and a very good specialist in his time,but in Europe.
This is a image of such piece from
ebay:
https://www.ebay.co.uk/itm/285589858212?_ul=GBI think that there is a small typing error on the first letter g in the word guarantee. I had a friend who was working in a accounting office ,he had a typing machine and he often complained that his machine had a defect and made the same typing errors on one or two letters from the alphabet. So by just looking the inscription, I can say that for me it is written by a typing machine and not printed by other type of method as printer .The traces of wear and the wrinkles are also very convincing, that this may be a piece, from the same period .
It would be interesting if this stamp was in one time part of the Roosevelt collection. I have tried a search trough Google, for information about the Roosevelt collection but unfortunately I couldn't find anything else, which could be useful. Only a short description for the sale in 1946.
This is the blog :
https://centurystamps.com/5-of-the-...-collectors/Probably if this stamp is proven by some other source as classic_paper pointed out in his publication, it would be attractive item for the most of the collectors.