What is it and is it harmful

Question

I have what looks like a white semi-circle egg that’s coming up from my lawn. They range in size. When you step on then, a brown dust comes out!

Answer 1

It sounds like a puffball mushroom, which can be white, gray colored or brown. Here is more info on them:
https://en.wikipedia.org/wiki/Puffball

This article will help with keeping them from growing in your yard:
https://www.gardeningknowhow.com/lawn-care/lgen/eliminate-mushrooms-in-your-lawn.htm