[Jochs]

After recent rains, these rather large mushrooms sprung up. These in recent years have grown in a big fairy-ring around one of our maples.
I think these are Eastern Flat-Topped Agaricus(Agaricus placomyces), which may be toxic to some people. The fact that these do grow in fairy rings makes me believe that my cousin ate these about 30+ years ago and got sick. I was told that fairy ring mushrooms will make you sick, while my book says the Fairy Ring Marasmius is an excellent edible. I could see someone being told fairy ring mushrooms are good, then seeing these and the edible fairy ring marasmius and choosing the bigger ones to eat instead of the small marasmius.

[Bachflock]

As far as "fairy ring mushrooms" will make you sick that is not accurate because there are some edible can sometimes be found in fairy rings. This is the right time of year for Agaricus to start showing up - I just found one in my yard. I didn't key it out but I suspect its a horse mushroom.

[Jochs]

The Fairy Ring Marasmius, which these clearly are not, are an excellent edible, according to the Audubon guide. However, an inexperienced person who heard that fairy ring mushrooms are edible might go after the larger mushrooms like these,( If given a choice to pick a small or a big mushroom, who wouldn't go for the big ones?) This is why it is good to make sure that you know what you are picking. Also, there are toxic species of Clitocybe that grow alongside the edible fairy ring mushrooms that can easily be picked by mistake by an inexperienced mushroom hunter.
Fairy Ring Marasmius are edible, but not all mushrooms that grow in fairy rings are edible.

[Jochs]

I'm reusing a previous thread from a year ago because these mushrooms are back this year, a month later compared to last year. I think these are Yellow-foot Agaricus. (Agaricus xanthodermus) They smell weird, and not like anise like a Horse Mushroom would. I am doing a spore print on one right now. (Edit: spore print chocolate brown...like a flat-topped agaricus or yellow foot agaricus...either way, not something I want to eat!)
The veil is cottony, and the gills are brown.
Here are some pics I took.

[Jochs]

The Yellow Footed Agaricus is native to the Pacific Northwest, and these are in my yard not in the Pacific Northwest
I originally thought these were Eastern Flat-topped Agaricus, I also suspected they were Horse Mushrooms. I am concluding they are Eastern Flat-topped Agaricus (Agaricus placomyces) which is poisonous to some people.
Horse Mushrooms have a Blackish Brown spore print, while this one has a chocolate colored spore print. Needless to say, based on the spore print and foul smell, these will only get eaten by the lawnmower.

Since these are potentially poisonous, and again this year are growing in a fairy ring, it is best to identify mushrooms in fairy rings before eating them. Some fairy ring mushrooms are good, others are poisonous. Saying that fairy ring mushrooms are poisonous or edible is not a good generalization. The key is what kind of mushrooms are in the ring, not the fact that they are in a ring.

[SWMichRealtor]

Thanks Jeff,

This is good work by you. Interesting that you read that the a. arvenis has a blackish brown spore print vs. a chocolate brown. Be careful getting that subjective. To me, unless you are going in with a microscope, I am not able to define the difference between dark brown and really dark brown.

The Fairy Ring mushroom is probably the worst named mushroom of all time. Many dozen varieties of mushrooms (both choice edible and scary toxic, and everything in between) grow in rings.

An uncareful, poorly educated forager may (MAY, if he/she is increbibly stupid) harvest and eat mushrooms because they grew in a ring and there is a good eating mushroom named the Fairy Ring.

Scary. Those guys will get a 48 hour stint on the toilet, if they are lucky, and hopefully that'll cure their stupidity.

Ed