Michael sent me mail art from Germany in this envelope with a nice WWF postmark.
The iris on the stamp made me think of the Sunday Stamps theme today - flowers.
The current definitives of Deutsche Post feature flowers, and as far as I can tell there are 25 of them ranging in value from 5 to 500. I have received quite a few - iris, tulip, carnation, bleeding heart, allium, and daffodil (sorry about the blurry scan, it was on the edge of a package). I think the covered up stamp is a marigold. I also find it fascinating that the denomination is in cents (e.g. 145), rather than euros (e.g. 1.45).
Update: here is a link to a picture of the whole set.
The stamps are relatively large compared to definitives from other countries, and I think they do a great job of showcasing the flowers on them. For links to more flowers on stamps, head to Sunday Stamps.
And here's the fascinating art zine that was inside.