A complete listing (according to my notes) of the forgeries of 19th century US envelopes appears in Part II of the UPSS Catalog of the 19th Century Stamped Envelopes and Wrappers of the United States, 2018, 4th Edition.
I didn't find the specimen item in the UPSS Catalog of United States Stamped Envelope Essays and Proofs. It does look familiar and might be a postal card essay. I do not have a copy of the UPSS Historical Catalog od U.S. Postal Card Essays and Proofs.
All of the UPSS catalogs are available through the APRL or for purchase at http://upss.org/code/publications.php