Looks like St. Augustine grass to me, but it also kind of looks like Centipede or Carpetgrass. Where are you located?

It isn't S. ravennae, from which the flower stalks will extend up to 4 meters over 1 meter foliage. The flowers look similar, however, and it looks like there is a white mid-vein stripe on the foliage...another similarity. Here is my stand of three S. ravennae this year: The plant you show looks like it has been mowed down during the growing season, witness several stubby green leaves with squared edges. I don't know what hardiness zone you are in, but many very flowery grasses will reseed in temperate zones.

Ive never seen it flower, we mow our lawn regularly. I thought it was smooth crabgrass or dallisgrass by looking on UCD website. I used Ortho Weed-B-Gon MAX Plus Crabgrass Control years ago & didnt work. Just a few days ago I used bayer all-In-One lawn weed & crabgrass killer. I went to take a pic last night looking for a seed head or flower (there was neither) & the bayer looks like it might be working, time will tell. If I see a seedhead I will post a pic. Thanks for the help.

oh, been there, had that...the shady parts of my garden were totally overrun with it when I bought this house at least there's a way to selectively control it...Acclaim. Although you don't even need to do that when it's 100% of the grass in an area, you can just kill it with glyphosate. It's almost completely gone. Of course with most of my neighbors having it in their shady areas, I will be forever fighting it