The one of the right looks like yellow nut sedge to me, which is a dreadful welcome to you in your new home. Could you give an in-focus picture of that plant?

If it is nut sedge, you will need to get something that will work on nutsedge, as Round Up won't do anything to it. I have used Sedgehammer to good effect, and someone in the Name that Plant forum reported success with Spectracide.

Oh wow I didnt even come across that one in my orginal google searches. Please see additional photos and let me know if any specific angle that would be better. I'm on the south shore of long island if that helps. Thanks again for quick reply!

It appears to be nutsedge. But the proof are the nutlets on the root tips. the only way to find them is to dig out a plant instead of pulling it out.

See http://ipm.ucanr.edu/PMG/PESTNOTES/pn7432.html

Well, there's another way - did these plants grow crazy fast after you mowed? Looked like you didn't mow them at all within two days?

yeah they grow crazy fast after a mow....and they have triangular stem so think we have found the culprit... thanks for all the input i would of never figured it out. cant believe how many diff types of weeds are out there. i ordered generic sedgehammer called sedge ender...will see how it goes. thanks again!

Good luck with the fight!

The triangular stems are another way to identify sedges. The other weedy grass could be either crabgrass or quackgrass. Without seeing a flower/seedhead it's very difficult to i.d. . Very easy to pull out by hand. If you pull, rather than dig sedges out, the tiny bulbets will remain in the ground, and grow new plants.