Here is a polished Kentucky agate. It a great mineral found here in the state and while it does not quite fit fossil theme of this blog maybe it contains some fossilized moss.
UPDATE: A fellow KYANA Geological Society member looked over this entry and pointed out some issues. She pointed out this agate formed inside a brachiopod. Remnants of the shell can be seen around the edge. So this really is somewhat of a fossil. Also it should be classified as a rock instead of a mineral.