There's already plenty of threads for covers, but I like the idea of a focus on fragments/pieces.
Some of my faves:
Illegal use of #78 as a revenue on a piece of photo backing, the studio of "Hamilton & Tidball" in San Francisco.

An R5a privately rouletted.

R5a part perf Major double transfer T5 on a Wells Fargo fragment. This is the ONLY example of the T5 DT I have ever seen that was imperforate vertically rather than horizontally. A one-of-a-kind piece.

Four 2-cent Trans-Missippi, including a pair, used illegally as revenues on a document fragment. I really wish this one was complete.

An R15c bisect, as yet unattributed, on a fragment of merchandise packaging.

Several R19a privately perforated sewing machine perfs (shut up Jim!

) on document fragments. Michael Aldrich had a group of these about 10-12 years ago, all with Philatelic Foundation certificates. All badly faulty, as most examples are. He was selling them on
ebay and kept dropping the price until I had no choice but to buy them. I'm glad I did, as other than one reasonably sound example offered by Eric Jackson (which I subsequently purchased), I have not seen any other examples of the R19a sewing machine perf offered on the market since.



Another piece of packaging.

A cover back showing several revenues used illegally as postage. Unfortunately without the front there is no context, other than one handstamp that looks to be French.

Great cancel aesthetics on this one.

An example of the newly-listed R112b imperforate stamp on a stock certificate fragment.

Example of R112c sewing machine perfs on a fragment, emobssed seal of the Port Wardens of the Port of New York with saling ship at center.

Example of the R135b 2-cent invert on a check fragment with nice socked on the nose cancel...

... and to go with that one, how about the R151a 2-cent invert?

And lastly a proprietary match stamp (RO135) used illegally as postage.
