Mine would pop up overnight. And they were so sensitive and so fragile that just the sun coming up seemed to make them dissolve.I don't think it's safe to rely on anyone here to identify a mushroom, it's too easy to get wrong.
Where there was one there will likely be another. Fortunately they tend to pop up overnight and you can easily pull them before Paxton starts moving around.
That mushroom spore could have been hanging around in soil mix for years before popping up so I wouldn't knock myself trying to figure out where it came from, just keep an eye out. Something changed in the environment, likely humidity; once it changes back the mushrooms will disappear as quickly as they came.