This is the result of the storm last Sunday night. Earlier that day I mowed in the 'far east' (we nicknamed sections of the yard because it's big) and had made a pass around the edge of the 'north 40' (because it's behind a set of bushes and we can't see it from the house) but the grass wasn't overly-long, so I didn't finish there, and I know the tree wasn't split and down then.
We had almost 2 inches of rain that night, and combined with the rain we had the previous Thursday, we STILL have puddles in the yard today. I tried to mow this evening around the puddles, and when I got back near that part of the yard, I couldn't figure out what was on the ground blocking my path (it's been dreary and foggy here ALL DAY). A couple of those thunder-booms sounded like they were in my yard that night, and apparently, one of them might have been!