You have some Stars of Bethlehem in your lawn (Ornithogalum - probably this one https://upload.wikimedia.org/wikipedia/commons/thumb/0/03/Ornithogalum_umbellatum_close-up2.jpg/1200px-Ornithogalum_umbellatum_close-up2.jpg). Some Ornithogalum are tall and pretty; these are most likely just low white stars like the ones I've linked to.
If you don't mow them, they will bloom in late spring (June in northern Zone 5). The flowers are white stars and bloom for only a few days. I agree with you about this species of Ornithogalum - they're weeds. I have them in both lawn and garden, and actually spent over an hour yesterday removing dozens of them.
If you want to remove them, I suggest using a Japanese garden knife (sometimes called a "hori-hori"). Insert the knife at least 5-6" deep, then wiggle it a bit to loosen the bulbs. This is easier in garden than lawn. You may have to just dig up the clump, remove the bulbs by hand, and put the clump back in the lawn.