It's hard to see a weed. I see something that looks like tall stalks.

Where do you live?

What kind of grass do you have?

I live in the high desert in southern California.

I honestly don't know what type it is since we have only been living here a couple of months.

I took your picture, tuned it up, and cropped in on what appears to be the weed with seed heads. Maybe this will help someone to id the plant.

The surrounding grass does not look too much different from the weed. Could the seed heads be from the same plant? I'm thinking you have a prairie grass lawn. Do the seed heads come up within a few days of mowing, or does it take a few weeks for them to form?

Here I have more photos and we mowed the lawn in December and we have not mowed it since and since there were no weeds in the winter.

Looks like there is not that much good grass left either from what I can tell.