This is a hard one, as it appears to be a very sick and spindly plant that looks like it has grown horizontal and then sent up vertical shoots. Also only 1 flowerhead has fully emerged. Although it looks like an annual, it could also be a very young perennial which is flowering due to stress. I'd suggest Eragrostis leptostachya. Main reasons for this ID, are the yellow glands below the spikelets, short scattered hairs at the sheath orifice and widely-angled (in the only flowerhead fully emerged) leaden-green spikelets. Spikelets appear the to align with the length (3-8 mm long) and no of florets (4-12) of E. leptostachya