I decided to pull the plug on my mycelium culturing in the spent ale grains project. The stuff in the glass jar and the clear plastic container was not really doing anything. When I pulled it out there seemed to be a layer of black mold on it, and the odor of fermentation.
However, when I opened up the stuff from the steel cans, that mycelium seemed to be growing really, really fast. Maybe it was just a white mold. I packaged this after freezing and drying out the old ale grains again, maybe it got more sterilized, or perhaps the lack of light had something to do with it. So maybe it is possible to grow the shiitake in the spent grains.
Shiitake spawn definitely seems to like the potting mix, so I am putting most of it in that. I repacked one of the steel cans with the old grains; I probably contaminated it though.