Fortunately, the issue pictured is not a fungus that infects grass. This is a slime mold, and it will go away almost as fast as it appeared, at least during dry weather. You can learn more in the University of Kentucky Extension fact sheet "Mulch Mushrooms, Slime Molds, & Other Saprophytes." (Its image labeled number 10 is an example of the kind of slime mold that you're seeing.) Slime molds only feed on other microbes, so are harmless for the lawn and any garden plants nearby. The low amount of direct summer sunlight is probably a contributing factor since it keeps any water (rain, dew, or irrigation droplets) on the grass blades for longer into the day, allowing organisms like slime molds to thrive. Turfgrass needs full sun to grow best (6-8 hours or more in summer, though fine fescue can handle a little less), so if it happens to be thinning-out in the same areas you find some slime mold, that might be a contributing factor.

Miri

Miri, 

You're welcome.