Kingdom: Fungi
Phylum: Basidiomycota
Class: Agaricomycetes
Order: Agaricales
Family: Amanitaceae
Genus: Amanita
Species: A. muscaria
Binomial name: Amanita muscaria
Common name: Scarlet flycap, Fly agaric ,Fly Amanita

Amanita muscaria is a poisonous and psychoactive basidiomycete fungus. It the most conspicuous mushroom seen in the autumn season in New Zealand. It is native throughout the temperate and boreal regions of the Northern Hemisphere. Amanita muscaria has been unintentionally introduced to many countries in the Southern Hemisphere, generally as a symbiont with pine plantations, and is now a true cosmopolitan species. It usually associates with various deciduous and coniferous trees (especially radiata pine and silver birch) in New Zealand but is increasingly being seen in southern beech forests where there is some concern it might take over from native beech associated species.
It is a large white-gilled, white-spotted, usually deep red mushroom whose cap can be up to 13cm diameter. Gills, stem, flesh and spore print white.

Skull and crossbones1.jpg This mushroom is  poisonous

Amanita muscaria first appears as a white cap

Mushroom Scarlet flycap Amanita muscaria-9.JPG
Then as a red dome.
Amanita muscaria Scarlet Flycap -001.JPG

Amanita muscaria with a wider cap.
Amanita muscaria Scarlet Flycap -002.JPG

Showing gills and skirt
Amanita muscaria Scarlet Flycap -003.JPG

Mushroom Scarlet flycap Amanita muscaria-35.JPG

An old cap with rim turned up.
Mushroom Scarlet flycap Amanita muscaria-36.JPG 

Amanita muscaria growing under beech trees in Otago, South Island.
Mushroom Scarlet flycap Amanita muscaria-37.JPG 

Thanks to Wikipedia for text and information: