I stumbled across The Evolution Store, a source of reasonably priced biological items, and though you might be interested. Here's a sample of what they have...
Pretty botanical prints.
Ben's from rice growing country, so this one appealed to me -- not to mention the colors are great.
The colors here are so great -- I'd order the poster, and then build a room around it.
Cherries -- these could work for so many different types of rooms -- kitchens, rooms with a lot of red and black, even for a different twist on cherry blossoms in a room with a lot of Asian elements.
Lots of interesting marble coasters.
Skeletons!
And last but not least, fossils!