Trying to identify this weed taking over my yard .Also how to kill it. It has runners that are along the ground under the grass. Has tiny hairs on the stems. I don't see any flowers on them. The pictures show the the where it emerges from ground and what it looks like undisturbed. Also a pile I got when I started dethatching my yard. Not sure if it matters but I live in the Pacific Northwest and my grass is bluegrass/ryegrass/fescue. Please any information and/or ideas are greatly appreciated.