Jersey

Jersey was surrendered to German forces on 1 July 1940.  The Germans would remain in control of the island until the close of World War II.

In the years since, the provenance of these stamps has been disproved.  They are now widely considered to be fantasy issues created post-war, and they are mentioned in Michel but not listed or valued.  Nonetheless, they are an interesting addition to any German collection.

For more on this interesting set, I highly recommend you consult the writings of Dr. David B. Ganse.