I have an invasion of some white stuff in my yard and it seems to be spreading throughout. It looks like what I can best describe as a snow-looking fungus. I haven't dared touch it for examination. The odd thing is we have lost 3 trees in the last 2 years that are in this same area. 1 tree I am not sure what type it was for sure but the other two were Mimosa Trees. Any idea what this white stuff is and if this may be the cause of the tree deaths?

Lupe

When you lose a tree there are a lot of roots in the ground to rot, and the fungus (many types, I'm taking an educated guess that this is one of them) are mostly out of sight. I'd be willing to bet that all of our recent rain has inspired the fungi to send fruiting bodies up to the surface. It's not what caused your trees to die (Mimosa are famous for living fast and dying young) but it is the cleanup crew there after the fact.