Hi - Is this grass in a sunny area or shade? This has similarities to a type of zoysiagrass (in sun) or fine fescue. Although fine fescue prefers the shade it can grow in the sun if it doesn't have much stress from foot traffic. This could slowly make bunches that go relatively unnoticed over time. Nimblewill could also be a possibility. https://extension.umd.edu/hgic/topics/nimblewill
If you have a seedhead from one of the plants, that could help us identify it.