Which mushrooms are poisonous?

Are the mushrooms in my backyard poisonous?

• I'm worried my dog will eat the mushrooms that keep popping up in my backyard, and I don't know if they're poisonous. I can't find any pictures or info online about types of mushrooms that are poisonous. I couldn't find any pictures that look like my mushrooms either. I live in AZ, can you help me figure out what kind of mushroom this is? These mushrooms are small and cream colored, and the tops are round balls and look like popcorn, like this http://www.flo-thru.com/Images/MushroomPopcorn.jpg When I pull them out of the ground, the insides are bright orange and gooey. I should have taken a picture, but I just threw them all in the garbage. How do I know if they're poisonous? Will my dog eat them? I'm worried.

• Answer:

  http://www.azfungi.org/record/record/azimagelist you'll be busy there for a while..... http://www.azfungi.org/amp/arizonafungi.html this anything like it..... http://www.tanelorn.us/data/mycology/myc_index.htm how I got to the first one..... most backyard mushrooms are the 'little brown mushrooms' that grow from underground wood decaying, like an old tree stump or roots..... all of them are toxic.... if your dog is a puppy, then you might be right in worrying... but if it's an older, wiser animal, most likely it wouldn't even think to bother them unless it was watching YOU mess with them.... some of them do resemble a fun ball.... ya know?.... but my cats and dogs ignore them... all of them....so it's not something I worry over......your best move would be to ask your dog's vet if he thinks the dog might be in danger and what would be the symptoms of mushroom poisoning in a dog, so you'd know it was time to take it to the vet's office......