Hello, it's my first time posting here. Usually I can find my lawn answers by searching on Google, which most of the time links to this site; however, I seem to have hit a brick wall with my latest lawn issue.

Over the past few months, some type of grass-like weed (?) has invaded a region of my lawn. This area receives full sun. The weed grows in small, very thick patches. The patches of grass are about 1 sq ft in size, some larger, some smaller. The patches can be spaced anywhere from a few inches apart to a few feet.

It appears like normal thin blades of grass, except for the tiny green balls that grow on some of its blades. I assume these are seeds. These green balls look prickly, but they are somewhat soft to the touch.

Here are some additional pictures I took:

http://i.imgur.com/mN7y1.jpg

http://i.imgur.com/EtNod.jpg

http://i.imgur.com/mbonYh.jpg

http://i.imgur.com/eihZth.jpg

I have tried searching for similar photos of this weed, but all I've been coming across are irrelevant results, or similar looking seeds on completely different plants. I'm hoping someone here can provide me with an answer of what it is, and what I can do to treat it.

Thanks.