Reminds me of ryegrass - really big ryegrass!

Thanks Carol. Interesting suggestion. It’s over 2.5’ tall. I don’t think ryegrass gets that tall (or wide). That said, I’ve noticed shorter grass with similar blades growing near the lawn. I like it whatever it is except that it was busy spewing seeds all over an area where I don’t want them. I moved it to where its progeny can duke it out with the J. stiltgrass my neighbor is harboring.

just because of the wet spot and the selfseeding

could it be Deschampsia cespitosa?

the leaves/ blades have parallel pin stripes when you hold them against the light

and quite sharp edges

Thanks, but I don’t think that’s it. There were no visible pin stripes (I haven’t held them up to the light; will check next time I’m there) and the blades didn’t have sharp edges.

if rye gras is Lolium, the seeds do not fit

going by the seed heads, it could be some kind of

Poa