yellow/orange spots

Just in the last few weeks, a yellow/orange spot has started to show in the grass under each of my maple trees in my backyard, about 6 feet from the trunk. We have only been here for 2 years and I remember these from last year also. Any idea what it could be? The stuff gets on your feet/shoes also. I will post a pic shortly.
Thx

 

Here are 2 different spots. Hard to get a good picture in the light.

pic 1

pic 2

 

hi am a newbie here!...i think it normal on grass to have yellow/orange spots...specially on summer days...