Hairy Bittercress (Cardamine hirsuta) is the name of that grass-like weed that has been flourishing in garden beds and lawns this spring. It's new to me, though a gardening friend in Landenberg reports that he has been dealing with it for at least five years.
Probably its most notable feature is its multiple skinny, inch-long seed pods along each stalk. Just try uprooting it and it will forcefully shoot out hundreds of seeds -- hence its nickname, shotweed.
According to the Gardening Know How website, "The leaves are alternate and slightly scalloped with the largest at the base of the plant. Tiny white flowers develop at the ends of the stems and then turn into long seedpods. These pods split open explosively when ripe and fling seeds out into the environment. The weed prefers cool, moist soil and is most prolific after early spring rains. The weeds spread quickly but their appearance reduces as temperatures increase. The plant has a long, deep taproot, which makes pulling them out manually ineffective."