White flat mushroom in potted olive tree

[DenverWagner]

Hello, everyone,
I have a small potted olive tree indoors and today I found a white mushroom in the soil. It looks very different from the mushrooms I can find about online. It is flat and looks just like a white button mushroom.
Is it harmful to the plant? Is it toxic to my cat? Should I remove it? Can I put it in a risotto?

Thank you so much for your help!

 

[Chuck]

No. Probably. No. No.

 

[alp]

Looks like a decent mushroom, probably edible. BUT DON'T TEMPT FATE!

 

[Becky]

"Every mushroom is edible, but some only once"