Recently my desert tortoise ate a poisonous mushroom that had come up in the backyard without my knowledge. Apparently due to the monsoon rains we get here in Tucson, these mushrooms can come up anywhere. Now that I have learned more, I know many of the poisonous ones are white or brown, but may be other colors too. My tortoise became very ill, was treated by a veterinarian who is a reptile specialist, but did not survive. I removed the mushrooms, but they've come back repeatedly. I'm looking into how to treat the soil so that mushrooms will be unlikely to grow there. A gardener told me to use sulfur, so I'm looking into organic sulfur to put down the ground to change the pH and prevent mushrooms from growing there. It's a very tiny patch of the backyard, and the mushrooms were really hard to see as most of them blended in with the grass. I wanted to warn others who have desert tortoises in hopes no one else has to go through this.