It appears that you have moles in your lawn. They can be pesky little guys and hard to control.  There are repellants out there for purchase-not always effective.  You can destroy the tunnels by packing the soil. Moles like to eat white grubs-the larvae of Japanese Beetles. They are the fat, white C-shaped worms that you will find in the soil under the grass. Eliminating those grubs will also help control the mole population. Grubs are best treated in early fall, but you can treat now-buying an insecticide that is labeled for use on lawns and controlling grubs. Good luck with the moles-often you can have them one year-but, not as bad the next year!