Hi Bob

It's really hard to tell what is the cause of this symptom in your lawn, however, it has the look of a fungus disease called dollar spot.  If you're in the eastern Nebraska area, it would fit with the recent weather patterns we've been having.  We don't recommend any treatment for it.  When the weather turns hot and dry again, there will be less of it produced.  If the lawn area is of very high importance, there are a few fungicides that can be applied.  If this is the case, please email me at <personal data hidden> and I can pass on the names and other information.

jfech