Here's one of my gems (thanks Grandpa).
From Soviet Occupied Germany, 1945.
Translation: Land Reform, Province of Saxony.
I think this stamp might be rice paper. At any rate, it is nearly transparent. And that's with its original gum.
If anyone knows more about this stamp and would like to share, I know I for one would be interested.

- Edited to fix grammar -
- Edit to include more info -
Well, I did find a few links on the
German Wikipedia site that reference a picture of a 6 Pf (100 Pfennige = 1 DM) stamp of similar design (it's green). While there is some text on the topic of land reform, there's not much on the stamp itself. One of the sites mentions (as best I can tell from the translation) that in 1946, money being tight, they switched to "cigarette paper", but I believe that may be referring to the 6 Pf stamp, as that stamp is clearly on a coarse, thick paper.
The land reform bit is interesting. (Note: I got this from an
article in English). From 1945 to 1949, the Russians imposed a forced "land reform". Any estates with 100 or more hectares, with the exception of Church estates and a few "experimental" farms were confiscated without any form of compensation to be redistributed to "new farmers" in 5-10 hectare parcels. The former owners, Junkers (even antifascists), Nazis, and large landowners -- "the distinctions between them were not sharply drawn" -- were driven off their lands, often quite brutally "without allowing them time to take their personal effects with them", and sometimes even murdered.