Wtt/WTB: Improper/Illegal US Revenue & Postage Usages

Am looking for any and all usages of U.S. postage stamps as revenues on document and revenue stamps as postage on cover. All eras (Civil War and post-Civil War, Spanish American War, early 20th century).

No usage too mundane. The only limitation is that for usages of revenue stamps on covers as postage, that they be in-period usages, not philatelically contrived ling after the fact.

I have plenty of U.S. revenues to trade, as well as lots of non-U.S. material (not organized enough to take wantlists for specific stamps, but can provide folders/lots from different countries).

Thanks for looking.