Would guess it to be Nostoc commune, a cyanobacterium that resembles algae or seaweed. A common issue in areas with poor drainage or high water tables but it will grow equally as well on gravel or paving, provided it receives periodic water.

I have similar thing. I think it is algae/moss. will show up on the area with lower elevation where the soil retain more water. I would get a soil test done and see if PH need to re balance to get rid of it. Also your lawn looks weedy. Might want to power rake using a dethatcher the whole lawn to promote grow and give it some fertilizer. Also might want to spray using post emergency before you power rake to keep the weeds at base.

My lawn used to looks like that in some area due to negligent and lack of knowledge.

Thanks. I will do that. It is weedy, stopped using Scotts lawn service.

I think for your lawn, it is now too hot so.

1. Might NOT need to spray the weed this year

2. Dethatch using a Sun Joe scarifier, about $100 online and make sure to bag everything.

3. water the lawn everyday for 2 weeks. The lawn will grow fuller and there will be lot of weed growing with it but it is okay and expected.

4. start mowing about 1.5 inch height and bag the clippings, then follow up by weekly mowing and bag the clipping.

5. fertilize the lawn monthly with an organic to fertilizer like Milorganite to add more good bacteria to the soils so later one you can leave the clipping and the bateria will break it down for you, but not right now.

6. water weekly after mowing grass about 1 inch of water

7. Come the fall, then you want to get a pre-emergent herbicide and get started on controlling the weeds. Winter then you don't do anything but come the spring before soil reach 55 F then you want to do second round of pre-emergent herbicide and by next summer your lawn should be green and healthy. Remember to keep fertilizing for a few years before you leave the clippings

8. If possible I recommend renting an aerator and do that twice a year to loosen up the soil, one in spring and fall.

Hope this help.