redneck crop circles?

First of all, not my term. Ted and Jim coined it. I've been dumping & spreading stall shavings and manure out in the pasture in bare spots (ie, the entire pasture) to help the nonexistent grass. This morning, I noticed someone poo'd right in the middle of where I spread shavings day before yesterday so when I was done, I went over with my pitchfork to spread that out. As soon as I got close, I found a giant hole right in the middle of the area I had spread shavings that was not there day before yesterday. It was about 6" diameter and almost 2' deep! It looked like it was dug with a post hole digger and the dirt taken by whoever dug it. The ground was not disturbed around it. The shavings went right up to the edge of the hole. No dirt anywhere from the hole and some shavings sprinkled on top of the bottom of the hole. About 10 feet away from that one was another one that was probably about a half foot to a foot deep. Called Jim out and started walking around looking for any others, cussing a blue streak the entire time just imagining broken legs.
Jim got out and took one look at it and started looking around for the missing dirt. Said same thing I thought. Looks like it was dug with a post hole digger. We stand there scratching our heads and call Ted.
I'm still cussing btw.
Ted comes over and takes one look at it and starts looking around for the missing dirt. Jim tells him not to bother, there isn't any. He takes my pitchfork and turns it upside down and starts feeling around the bottom of the hole with the handle. It's soft for about an inch then felt like he hit a rock. Meanwhile, Jim finds another one on the other side of the pasture. Now there are 3 of us standing there scratching our heads. Ted calls our neighbor Terry, who has cows, to ask if he has any mystery holes in his pasture while I gather rocks to fill the holes in with. Terry comes down and (yeah, you guessed it) 4 of us standing round scratching our heads.
Jim and Ted decided it was redneck crop circles. Terry thinks we have a varmint. Altho, not sure what it did with the dirt AND how it got thru the hard clay that far down.