further to previous response, Encyclopedia Britanica article
Ah thanks, I did have a look at the Britanica article which helped, hence I posted the link to help others too.
A more encyclopedic overview is available in Wikipedia [1] (experts can debate which is more encyclopedic, or even better, improve both of them ... ummm, well, improve one of them further). Although mortality was still in the 10s of % or so in the late XXth century, there's at least one Italian hospital claiming 100% cure with no sequelae for patients hospitalised within 36 hours of eating the mushrooms [2].
[1] https://en.wikipedia.org/wiki/Amanita_phalloides
[2] https://www.tandfonline.com/doi/full/10.1080/15563650701365834
@zleap they're mycorrhizal, thriving in association with many kinds of broadleaved trees. It's not rare, and it can come up in the same woods over and over, year after year. But I've never seen it in the numbers I'm seeing now, something about conditions right now.