It's probably a toad coming out of hibernation. I have uncovered three so far this spring. Two were rather small - 1" diameter, and one was closer to 3" across. They come up for some sun, then retreat at night until they feel it's time to emerge for the summer.

I have a ton of ground squirrels in my yard. Could it possibly be one of their holes...?

I have a huge problem with ground squirrels, and they make holes all over my yard, and I still haven't found a definate fix for them (other than my husband getting "rid" of them.) We live on a farm with grain bins, thats why they are here. You can try hosing them out, it lures them out of their burrows.

I have often wondered about snakes too, I have so many of those in my yard.

I realize it has been a long time since this was originally posted but after reading it I couldn't resist. SNAKE DO NOT DIG HOLES!! It is a common misconception that they do because they will use hole that are dug by other animals such as ground squirrels, moles, or toads but as far as digging their own they just aren't equipped to do it.

We have a huge population of chipmunks in our rose garden. They burrow and dig holes like the ones you mention. Do you ever hear a chipping or chirping sound that about drives you crazy before it stops? If so you could have chipmunks. I've heard mothballs work great, but I don't know if they hurt the garden or not. I'll be watching this thread with interest to see if anyone knows.

Ginni