A Comment, Info On France 1 C Imperf Blk On Yellowish Type 2 ?

@TiaT

It is not an adhesive label, but an imprint applied to a postal stationery item. In the early twentieth century people cut these out of the postal stationery and kept them in their postage stamp collections. Nowadays, most stamp collectors ignore them. Postal history and postal stationery collectors prefer to collect the whole item.

You example is as you describe because someone cut it out from a postal stationery item.

You might want to read the whole thread that provides all the information.

Here are a couple of example of an entire wrapper from ebay. The stamp design is printed on the envelope (wrapper) which is usually wrapped around a newspaper or magazine and sealed for mailing. You can find them listed in specialized catalogs for France, or worldwide postal stationery catalogs such as Higgins & Gage:
https://www.ebay.com/itm/276704145763
I agree with the other comments, postal stationery is usually collected as a complete cover, not as a cut out like the examples in this thread. Nothing wrong with including them in the back of your album with other unlisted items, just that there is virtually no collector market for them.