We've had a lot of mushrooms grow in our yard over the years but all have been typical shaped mushrooms until now. We discovered these growing under a Japanese Maple that we have growing behind the house. Weird looking things. Kind of grow straight up out of the ground and then fall over. Reminds me of the old sci-fi movie The Monolith Monsters. Don't know where they came from. Haven't planted anything new in the yard and the Maple tree has been there for 20 years. Flies seem to love them.