This is an Amanita muscaria, commonly known as the fly agaric or fly amanita. It is growing in the woods behind the house. Pretty, and used to be used as an insecticide when sprinkled with milk (hence the common name). Don’t eat it though, since it is classified as poisonous.
Usually with a bright red umbrella, ours seems to be the orange variety called Amanita muscaria var. guessowii, or “American fly agaric, yellow variant”.
More info on the Wiki about Amanita muscaria