Fungus and Disease
Brown Patch is a cool weather fungus that when conditions are perfect, can cause cosmetic damage but not kill St Augustine turf grass lawns.
During the cooler weather in Pinellas County, home owners my see curious crop circles in their lawn. Most likely those caused by brown patch - a cool weather fungus. Brown Patch is mostly cosmetic and lethal to the lawn.
Mushrooms growing in the lawn does not indicate you have a lawn disease or fungus in your St Augustine grass lawn. It means you have mushrooms.