Northern Utah. I can’t find any accompanying holes, and you honestly wouldn’t notice the bumps in the soil unless you walked in the grass, they don’t look like the vole or gopher mounds I see online at all; they’re quite small. Generally it looks green and happy.

My backyard has 6 locust trees and it’s very shaded, I originally thought it was maybe related to that, as we noticed the bumps when we moved in 2.5 years ago. Now these bumps are spreading to the front yard where there are no such trees and a lot of sun.

Google tells me maybe earthworms? I went and dug up a few newish bumps today and I don’t see any accompanying tunnels or anything, no idea what’s going on. It just looks like normal dirt all around and under them. Any ideas on who could help diagnose this?