That is most likely a slime mold. It's harmless. Usually that happens with a lot of wet weather, and cloudy days. It will go away with dryer air and sun. You can get some leaf yellowing, but if your grass is healthy it will outgrow that.

I love this quote, "unless you want many, you probably don't want any" -- perfect! Thank you all! I have been pulling the entire root ball out and then using the stems in flower arrangements.

Yes, L. inflata will try to blend in but the foliage is a bit coarser than L. siphilitica and the flowers tiny as you confirmed.

It looks like it could be Viburnum dentatum, Southern Arrowhead Viburnum. They aren't any trouble. Their leaves can be skeletonized by the larvae of a certain leaf beetle, (Pyrrhalta viburni). The link gives a couple other similar Viburnum options. https://www.illinoiswildflowers.info/trees/plants/south_arrow.html