This weed/grass has a single stem 8 to 12 inches long and about 1/16" in diameter. At the top is a tiny pine-cone-shaped bud about 3/4" to 1" long and 1/4" in diameter surrounded with a corona of very tiny white flowers spoking out from the bud. The bud is usually a brownish color above the corona and green below it. The slender stem is green and not circular in cross section - maybe square or pentagonal. It is fairly common here in the midwest at this time of year.
Can anyone tell me what it is?