On Fri, 14 Jul 2017 13:42:32 -0400, "Kurt V. Ullman"
wrote:

Have some things on my yard that I am not sure what it is. I have gone
to two garden shops and got two mutually exclusive responses.
After rains the last couple of weeks, I have a cottony cover on my
grass (I thought originally it was stuff from the cottonwood or some
weed sticking to the wet grass (see picture). However, soon I realized
that the grass in the area was turning brown in roughly the outline of
the cottony cover. One guy suggested fungicide and another just thought
I should fertilize and it would come back.
Any suggestion?
http://imgur.com/M3roAaC
http://imgur.com/3MsIWYL

The first picture appears to illustrate a multi-cellular filament
organism, which would mean it is mold, a type of fungi.

Here is just one of many articles on the topic.

http://homeguides.sfgate.com/mold-lawn-grass-70157.html