Bad. This is a weed called kyllinga. The spiked balls are actually seed heads of kyllinga, which you do not want to reproduce. Unfortunately, this type of sedge is the most difficult to control and resembles grass very closely. Kyllinga is about the same height of grass, but has a different shade of green and tends to have a glossy appearance. Very few herbicides even have this particular weed on their label and to get control of it, requires a lot of extra care. When this plant is killed, it will get a reddish-brown when most plants would get a yellowish-brown. Many times this weed will look it was killed (controlled), but it was only suppressed and can easily come back! Using the right herbicide and limiting water flow to these areas is the only solution. If negelected, kyllinga coverage could double in just one year.