What causes small golf ball size holes in the lawn no mounds present?

Could be chipmunks, bees or even possibly sinkholes. Have you checked the depth of them? Be careful in the event there are bees in there.

Squirrels digging up stored nuts

Sounds like squirrels or armadillos to me. We have them too but have decided that instead of conquering nature, we will just learn to live in harmony with nature. After all, they were here first.

Squirrels,and some birds digging for grubs,ive seen a bunch of birds muti hole an area in no time,I have also seen raccoons dig for grubs,The birds were the ones that surprised me.

I get those from frogs and chipmunks in my area

There may be some little critters digging holes in your yard. It may be a good idea to get your lawn care guy to look into it for you.

could be voles

Moles and Voles. Get some grub killer. They eat the grub worms. If you kell the grubs they go elsewhere.