I had an amazing discovery today - I found a fungus at the root of an oak tree in the back. I was walking the grounds again, and noticed some blackened protrusions near the base. I nudged it with my foot, and it broke off.
I feel fairly confident identifying it as conk, in scientific terms, DRYADEUS ROOT ROT (Inonotus dryadeus). It's common in oak trees (which this was), particularly where the tree has been damaged. It's often found following a wound caused by a lawnmower or other garden machine. It can injure the health of the tree, so I'll be keeping an eye on it in the future.
I took the photo below, using my MacBook's built-in camera. Tomorrow, I'm going to try to get a good photo using my QX3 Intel digital microscope. If I can capture a good shot, I'll add it to this post.