One of the cool things about being a woodworker is that you get to see wood in ways most people never do get to see it. Perhaps the classic example is eastern red cedar, which when freshly planed is a gorgeous pink shade of purple. Within a few days, it fades to the reddish brown most people are familiar with.The other day I was prepping some stock for my dovetails by hand class at Highland Woodworking. I like to use yellow poplar in these classes, because it's not expensive or fancy, so nobody's nervous about "wasting" "expensive" wood just for learning. It's also, usually, a vaguely greenish shade of yellow when freshly milled, and turns caramelly brown over time.
This batch of wood, though, had been put into the kiln without any initial air drying, and so things stayed pretty wet in the kiln for the first part of the cycle. The fungus had some fun with this stuff. I planed through some black gunk on the outside of the planks, and lo, the interior of the wood had some gorgeous red and purple staining, here and there, like cranberry clouds in a chartreuse sky on the cover of a science fiction paperback from the 1960's. Like this:
Unfortunately, this is just fugitive color in a few random pieces of lumber. Not enough to design a project around, and probably nothing that would remain visible for any length of time. Just another unquantifiable benefit you get as a woodworker.