Grass / Weed ?
Looks like annual bluegrass (also known as poa annua.) It's a weed grass that will die by summer in the heat and drought. It likes it wet and will move into lawns that have wet areas which has thinned the grass.
In the photos, the soil bare of all growth suggests that this area is under water sometimes, which has killed the normal lawn fescue. The annual bluegrass will tolerate those conditions, however, and is happy to do so. We have had abnormally high rainfall for over a year, and many lawns are drowning and seeing more annual bluegrass.
Improve the drainage in the area as much as you can. Here are tips and help with annual bluegrass: https://extension.umd.edu/hgic/topics/annual-bluegrass