After living in Japan for a few years, something odd happened to my physiology. I must have crossed some tolerance line for shiitake mushrooms, because it seemed like one day I just suddenly became super allergic to them.
It took me a while to figure it out, but whenever I ate shiitake I would get terrible stomach cramps, nausea, and, well, let's just say my system put the "shit" in "shiitake." I don't have this with any other type of mushroom, and from my internet searching it seems shiitake give a lot of people the same problem.
So I stopped eating shiitake, which is pretty easy because they have such an easy-to-identify distinctive flavor and haven't had any problems since.
Today I went out to a cafe for lunch, and ordered a fairly compliant poached egg salad. I noticed after a few bites that some shiitake were served on the side. I should have stopped but I was a little curious, I hadn't had a shiitake reaction in a few years, and hadn't tried US grown shiitake. Maybe things would be different.
Spent the whole afternoon on the toilet, and sadly lost most of my hard-won nutrition intake for the day. Was feeling rotten and depleted so for my evening snack I made the mental health call to have a slice of bread with chocolate peanut butter spread. Some extra carbs, fats, and sugars helped a lot.
So, shiitake, lesson learned, I'm backing off until a few more years when I'll forget about this and try again!