Amanita muscaria contains muscarine, but only traces of it, unlikely enough to kill a healthy adult with moderate doses of the kind that would be ingested deliberately for recreational or spiritual reasons.
That said I recall a case of an italian diplomat who cooked up a plateful of fly agarics for breakfast, and died because of it.
Anything CAN be lethal, the dose maketh the poison, drink enough water and it'll kill ya.
The clitocybe and inocybe species especially though, DO contain more than enough muscarine to be lethal, and I.Patilouardii, I.Fasciata and a couple of others can and do kill people, as do Clitocybe Rivulosa and C.Dealbata which are often mistaken for edible Marasmius species, they all pack a fuckton of muscarine.
I wouldn't eat ANY inocybe species, they are mostly toxic, although a couple contain funky quaternary amine tryptamine derivatives, or psilocybin, theyre almost all small brownish nondescript mushrooms that are notorious as one of the most intractable families to identify without the aid of a microscope, a specialist guide and chemical reagent tests.
You eat the red stainer inocybe, and chances are, you will die, theres a HELL of a lot more muscarine than the traces in Amanita species.
I got a good haul of amanitas recently though, A.Muscaria, all nice, firm specimens which had yet to expand and get maggoty, which they do bloody quickly, now in the form of nice dry amanita chips, finishing off the drying over a tray of P2O5, I think I might dose those today, although I am a wee bit scared of em to be honest, perhaps with a lil DMT it should be fun :D
Could you reference the claim of a fatality from A.Gemmata per chance? I am most interested in mycology and toxicology, and am getting bored reading the same old stuff
It also looks like nastier amanitas by far, A.Gemmata that is, wash those flecks off, and leave it with just that prominent ring and volva, what does it look like to you

some potentially useful members of that family look like the worst of the worst as far as suspects go, I happened upon what I am fairly sure was a load of A.Citrina (false death cap) the other day, but sure as hell I'm not going to pick them and run an extraction on em for the bufotenine content, as they really do look like death caps.