These mushrooms appeared in my office plant in under a week. Can someone give me the latest info.

Houseplants are a very common place of origin for fungi. Usually the people in the local area don't know what they are,because they come from some giant corporate headquarters far away. FOr example, I don't know what they are.
John S
PDX OR

This common species has gone through several name changes. Old school mycologists might call this one "Lepiota lutea". The current name is "Leucocoprinus birnbaumii":

https://en.wikipedia.org/wiki/Leucocoprinus_birnbaumii

I see these all the time in flowerpots and compost. They are not edible and can cause stomach problems if consumed.