Could be a vole if the ears are small and no tail. If so, they do a lot of damage underground.

How fat? Maybe she is expecting and looking for a place to have babies.

HARMFUL! We thought it was cute at first and possibly useful if they ate bugs, but they get into the walls through the little weep hole gaps in the brick and end up in the house or worse, having babies in the walls. After we plugged the weep holes with steel wool, we started finding piles of mouse poo and pecan shells all over: in the A/C box outside, in the crook of a folded up lounge-chair, in the small vinyl greenhouse...

Almost certainly a Texas or prairie vole. I have them by the thousands. I have never had them enter the house, although six cats with a taste for vole may have something to do with it. Two big fat ones live in the chicken house. They do dig burrows, and the holes can be big enough to trip you up, if you don't see them. I have had no sign of them eating the garden. I think seeds are more their preference. Aside from those two, I haven't seen one in weeks. It's the drought, and I suspect they've all gone deep to lay up in the cool. The cats have been going without all this time, but they're wasteful and only eat the heads, anyway. If you want to trap, they'll do fine most anywhere you release them. They are also said to be afraid of fake owls and hawks. They seem to be relative newcomers to most areas of Texas. Most literature talks about them being restricted to one or two counties, but they're clearly now in many places.

I am in Denton county, and have had them for many years. My cat has a taste for them as well, but there is no way she can keep up with the number I have. They make watering very difficult as it just runs down their burrows and comes out "heaven knows where". They are cute little critters, but my life would be better without them.

See link below. Is that the one?

Omar

Here is a link that might be useful: Vole

Boy am I glad to live on top of limestone!

Hmm, well, it has a long tail like a rat, and distinct pinkish ears on the side of his head. I haven't seen any damage like the pics in that link, either. I didn't think it was ugly enough to be a rat, but the pics I just pulled up all say "rat." Yuck.

If I put out rat traps, will the squirrels stay away or will it trap them too?

I suspect there is considerable variation in vole behavior from place to place. Here, for instance, there are no surface runs. The only physical sign you see is the barrow holes. They're very industrious, because my soil is more river rock than soil, and you're wasting your time with a shovel. Of course, the link was from a great distance away, and what is pictured as a vole is clearly not my variety. Mine look less mole-like and more mouse-like. They look more like a large mouse when they're foraging for themselves. When they live with sloppy chickens, they're much more handsome and sleek. I would guess that the best defense would be to allow no tall grass for them to hide in. Small furry potential meals are always leery of open spaces (as are snakes, for that matter). Voles have to eat constantly, so they have a hard time where they can be seen by hawk and owls.

Where there is one there will be more!!

Kylie

Rodents are not helpful. Kylie is so right. More and More...
They get in your house and all your stuff. They'll eat your plants stored in the garage for the winter. They'll tear up your attic and roof. Phone & elect wiring.. they're just nasty.

Snakes like to eat them. If you have rodents, you'll have snakes too.

It's not a possum by chance?

See my post on cottage regarding rats.

Here is a link that might be useful: Oh Rats

Lymphocytic choriomeningitis (LCM). This is a virus spread by the common house mouse. The virus can infect the linings of the brain and spinal cord. It's a serious disease, although many people get only mild infections. Mice shed the virus in their urine, saliva, and feces. People get infected by eating contaminated food or by inhaling aerosolized mouse urine or feces. LCM has two phases. The first lasts about a week and begins with fever, loss of appetite, head and muscle aches, nausea, and/or vomiting. There may be other symptoms as well.

The second phase happens just as the first one gets better. It may begin with symptoms of meningitis: fever, headache, and stiff neck. It may also begin with symptoms of encephalitis: sleepiness, confusion, and movement problems. There's no cure, but most people recover completely with supportive treatment. However, some people are left with permanent nerve or brain damage. About 1% of people with LCM die.