Great summary. There's only one problem with Amanita and mushrooms in general. As it seems, neither Amanita muscaria nor any species of Psilocybe family grows in Levant (and certainly not Arabia). And because the climate of those areas didn’t change much in the last 2000 years, there’s little doubt it was the same in the times of Saul. There is, however, evidence of using Cannabis in ancient Israelite ceremonies. Also, when you look at one pre-historic painting (see below) of Cannabis from Japan, the portrayed leaves pretty much look like mushrooms (but also poppy :D).

Cannabis was used in ancient Israelite ceremony, researchers find

(source)