Amanita caesarea is a very popular edible mushroom which is known and used as food for more than 2000 years. The early Roman Emperors were very fond of this delicacy, which is what inspired the latin name.
Amanita caesarea is an ectomycorrhizal fungus that establish natural symbiotic relationships with both, trees (Quercus, Castanea, Pinus) and shrubs (Arbutus, Cistus). It is a specie of the Mediterranean region, frequent in Southern Europe and less common in other European countries. It has also been collected in North Africa, Asia and Mexico, being this the only record for the Americas.
Caesar’s mushrooms fruiting bodies have an Agaricoid shape, i.e. a gilled mushroom with a central cap and stem, and always present a distinct ring and volva. But, the most obvious feature is its bright orange cap. Fruiting bodies usually appear from October to November in the Mediterranean region, in both siliceous and calcareous soils.
More info at:
http://info.uevora.pt/cogumelo/