Amanita mycelium is one of the great expanse mycelium, the strands will grow rapidly and extend hundreds of feet in a few years, that is why there seems to be a huge spreading of this
fungi.
As Alder Burns brought up, it takes years to learn identifying the different edibles and being able to differentiate them from the non edibles.
The only "short cut" to gaining this knowledge base that I am aware of is to find a mycelium group (mushroom group) and join them every chance you have to learn from the experienced mushroom hunters.
The absolute best way is to go through the college courses all the way to PHD, then you would be able to identify any mushroom on the planet, that does take about 10 years to complete though.
I have a friend that is a mycologist and I only go "shrooming" with him. I have lots of different species on my
land but I do not wild harvest them, I grow mushroom logs and bags instead, that way I can't mess up identification.
You only get one chance with mushrooms you either get it right or you are very sick or dead.
Redhawk