That is some fungi!  I believe it is a type of mushroom and not mold.  It is really difficult to identify the specific variety, but most of them are all caused by organic matter such as an old tree or roots that were removed a long time ago, or even construction lumber left. I found an article which should help identify it and treat it.  It is actually not a bad thing.  If that area were not so rich, it would not support the growth of this mushroom!
Grass around it looks healthy as well!
https://ipm.ucanr.edu/PMG/PESTNOTES/pn74100.html

Thanks for reaching out to OSU Master Gardeners!

Leslie
EMG