|my yard has small clumps of dirt that if you gentlly scrape off the top, there is a 1/4|
|Based on your description I am not certain what is causing the holes. With mole crickets I would expect a tunnel. If it is just a small diameter hole, I would lean towards skunks foraging for grubs or insects. They are nocturnal and their faint scent as well as freshly disturbed soil might interest the dogs. Another possibility is birds such as grackles, also foraging. I would suggest you consult with your local county extension and see if they have any suggestions, in part based on the time of year and knowing what is most frequently occurring in your local area. If it is something that requires control, they will have the most up to date information on what to use and how/when is the best time to apply it for maximum results. Here is the page with contact information for the local offices.
Good luck with solving the mystery!