But I've been collecting these mugs and it's really difficult to find a clear list of what designs exist. So I thought I'd do people a small service and try to make one. These are all the ones that I know of. I will update if/when I find any more.
All descriptions give links to the images, where possible (mine are in storage, so I can't take pictures of them).
Persimmon --- this is the artist's main site
Oak and Acorn
Pinecone (which I've also seen with gold leaf)
In the interest of completeness, there are also two kids' mugs, which have a different shape but are by the same artist. Bunny & Goldfish