It would help to see the whole plant, but with just the seed shown, looks like grass to me.

Here is an image of a small section of the lawn. If it is grass that would be great because there are thousands of them that grew like that within just maybe a week or so. I would take so much work to pull all of them. If it is indeed grass, would it be ok to just let it grow some more so there will be more grass/get thicker as I lost some due to the sprinkler system malfunctioning (it was on constant ray delay when there wasn't any rain at all).

Yup, your grass went to seed. Also, the browned out grass isn't necessarily dead; it's likely just dormant in the heat without as much watering. Those of us without sprinkler systems have this happen every year; it comes back green in the fall, or if it rains a bunch, when it gets less hot and dry. The grass is trying to spread itself, so it'll ripen that seed pretty quickly, so you can probably mow or clip it pretty soon, if you want; once the tight stems open up, it's definitely ready.

Well, there is no doubt it is a grass! But whether or not it is a weed or a desirable type of turf or lane grass is another matter. There are far more species of weed grasses - quack grass, pasture grass, couch grass, barnyard grass, broomsedge, annual blue grass, crabgrass, stilt grass, etc. - than there are turf grasses.

If the growth rapidly outpaces that of your regular lawn even with frequent mowing, it's a weed and should be removed or eliminated.

@BlueberryBundtcake - 6a/5b MA You are most likely right. Considering that it is all over the lawn and started to grow at pretty much the same time everywhere I somewhat doubt it is weed. If it was weed it would have had to be there for a long time (seeds flying all over the lawn for a few seasons) and just waiting for the soil to get dry when it can take over the grass.

@gardengal48 (PNW Z8/9) At this point I don't really want to mow the lawn because that would spread the seeds. If it is the same type of grass that I have that is great. But if it is other grass than I would be in trouble having to pull many 10s of thousand of weed instead of pulling thousands of weed grasses (and this is a pretty small backyard of maybe 600 sqft).

It is obviously NOT the same kind of grass that is growing in your lawn....otherwise it would look just like it (and it doesn't). Weedy grass seeds can blow in from anywhere and can also attach themselves to clothes, shoes, pets, wildlife that might be visiting, lawn mowers and anything else that could come into contact. That's why lawn purists spend millions of dollars every year on pre-emergents and other herbicides to keep them under control.

btw, if the seed heads are not ripe - and judging from your photos they do not appear to be - ten there is minimal risk of spreading them by mowing. They won't ripen and spread if cut off :-)

Here's our grass that's gone to seed ... regular, northern lawn grass, not weed grass (it's hand weeded):

Unripe:

Ripe (or close):

The ripe seed isn't much ahead of the unripe, probably a couple days. There are multiple varieties of grass in the lawn, so I couldn't tell you which species this is, but it's not a weed grass. (A weed patch - Pilosella - was being removed nearby before mowing.)

is it really a lawn.. if you dont mow it regularly ...

in my MI sand ... all non-irrigated lawn go dormant in july/august ... its normal ... its nbd ... the grass is not dead.. its heat/water dormant ....

but also ... if its not mown .... its might be called a meadow... or pasture ... and all kinds of things pop up ...

perfect your watering .. if you choose to spend money that way .... mow regularly.. and use a good weed and feed at the appropriate times of the year.. you you can easily get back to a LAWN ...

and.. if you just keep it mowed... most weeds will not flower and go to seed.. so simply growing the grass properly.. so it gets thick... will stop future weeds from invading ...

my 5 acres were previously horse pasture.. i mow it and call it a lawn ... wink wink .. lol ... but the only things green in the heat of summer.. is all the weeds in the lawn ... so at least some of it is green ... i also leave about an acre of it unknown .. and i call that the wildflower meadow ... saves me time on a weekly basis.. and its interesting to watch the flower show progress over the growing season ...

so i guess.. the moral of the story is.. what are you growing.. what do you call it.. and how do you cope or deal with it ... and once you define all that.. it should be easy to figure out how to deal with it ...

ken

I do mow the lawn on a somewhat regular basis, i.e. like every other week or so. @BlueberryBundtcake - 6a/5b MA that second picture is exactly what I had maybe a year ago or so. That sprouting grass was about the same height as the rest of the grass. What worries me is that what is growing now is a lot taller, like 6" or so compared to the rest of the grass which is just maybe 2" at best.

@gardengal48 (PNW Z8/9) I took your advice and just mowed the lawn today hoping the seeds don't spread, assuming they are indeed bad seeds. I just can't explain how I suddenly (within a week or so) I get thousands of those pretty evenly distributed over the entire (small) area. I also put out some fertilizer and put an extra cycle of watering on in the hopes that if this is weed the grass will take over.

I should clarify, our seeding grass is about knee-high over one hand high grass.

Solid chance this is poa annua, also called annual bluegrass. It's a pain in the *** to get rid of. Pre-emergents usually control it (apply in the fall). To kill it while your existing grass is active, you need to find a selective poa annua killer. I used this to get it out of my bermuda https://www.domyown.com/negate-37wg-p-16655.html

I could be wrong, but it looks like what I had. Basically it grows faster than other grasses, and seeds very quickly (make sure you bag clippings when you're dealing with this stuff).