What is this? Saw it in Nebraska

[Hobbes]

Looks like pocket gopher is correct.  I've never looked into what was making them.  Here's an illustration that I found.

[Tail Feathers]

Well if they use a plug to hide their tunnel that would explain it all.  Thanks chad and Hobbes.  I never saw a gopher but that place must have a lot of 'em.

[Hobbes]

I've probably been told that's what it was once before but frost heave sounded good. 

[Chad]

  Learning new critters and their sign is a big part of the fun when hunting new country

[Tail Feathers]

This one sure puzzled me Chad.  I looked at several and never found a hole (but I was mostly looking for one in the center) and that stumped me.