That is a very cool looking mushroom, Jim. I really like the looks of it. My only nit is the parts of the edge that go so soft in places. I’m not sure what iso the camera you used can handle without the noise getting out of hand, but I suspect you could go to at least 400, which would have given you another couple of stops at the same shutter speed. The background would have been more of a problem, but you can always add blur in processing.
Jim, I find myself arguing against a stack here. Since the mushroom is mostly in focus, selecting the BG and doing a field blur on it would pretty much take care of the business issue.