Been published a little while now, so I'm probably well behind the curve on this, but I just ran across a book called Woodcut by Bryan Nash Gill. (Incidentally, good artistic and printing credentials to that name, with Nash and Gill.)
So, they're large size prints taken from the cross sections of trees. Which on the face of it makes me go "Oh, well, o-kay..." Of course a lot of art makes me do that, but apparently that's because I'm a philistine, which is probably absolutely true. However, despite my natural inclination to scoff and point out the 1000 more useful ways to use wood, I find myself fascinated by these. Click on the link and actually take the time to look at the sample pages in full screen; I reckon it's worth it. And that's from someone who inevitably skips the how trees grow/study the growth rings portion of every woodworking book owing to terminal boredom.