This is a general revenue stamp issued in November of 1862 from the state of Prussia. My 1992 Erler Norton Catalog of the Adhesive Revenue Stamps of Germany volume IV lists it as #11 (15 silber groschen) with gray black center. It catalogs at .20 U.S.
The Erler Norton catalogs are very useful and complete, but the catalog values are notoriously low. If you could find your stamp in a dealer's stock, you'd probably pay $1.00 - $2.00. Dealers on
ebay, who assume you don't have a catalog, would ask more. On a document, you'd probably pay at least $5.00 for it, depending on the document.
As revenues go, the Barefoot catalogs (U.K.) tend to price on the high side.
Hope this is helpful.