Any ideas on how to keep critters out of the yard?

We had the same problem last Spring...and this was in our fenced in yard...very peculiar. Go to your local home improvement store (Lowe's, Home Depot, etc). There is something you can buy to put on your yard that helps keep this from happening. I can't remember the name of the stuff, but it worked for us.

MSU- recommends mothballs for armadillos.

https://www.msu.edu/~nixonjos/armadillo/problems.html

I was going to say mothballs too.

If you think it may be after grubs. You can buy a fertilizer that gets rid of them.

Try a Tomahawk Live Trap :)

If it is armadillos they are looking for grubs. Treat your yard for grubs and they will not be so attracted.

I would also suggest the grub killer. We had a few skunks coming around at night, and they were tearing up the yard digging for grubbs. The little holes got so bad that the lawn became bumpy and difficult to mow. Once the grubs were gone, the skunks stopped coming around. GL!

If whatever it is is feeding on grubs then treating for grubs will most likely resolve the issue. There are organic solutions for this that take longer to work but resolve the issue for several years and there are chemical quick fixes. If you have problem areas there are several non-toxic organic sprays that smell terrible to apply such as hot pepper wax. These dissolve quickly when it rains but prove to be pretty good short term solutions. Sounds disgusting but you can also try Coyote Urine. You are literally marking the spot of another animal which is a predator and when the space is plentiful smaller critters don't want to be anywhere near that stuff. (not my favorite resolve but it works)