This yellow subspecies is related to the bright red Amanitas that people recognize immediately. These were dinner plate sized. They range throughout the USA but are more common in the Northeast. There is literature that says these should be called Amanita muscaria var. guessowii to be absolutely correct, and since I can’t prove it I’ll just include the information.
They are a fall mushroom growing both under hardwoods and conifers from September through October, maybe into November where weather permits. They appear singly or in groups.
This picture was taken in Tylersport, Montgomery County, Pennsylvania, on October 8, 2012.
You can check out these web sites for more information.