Noticing a lot of these sign posts topped in a patch of grass. Is this a bird's nest or has the grass grown up through the hollow post and out the top? Hard to think it's the former, because it's seems to be green and living, not dead straw some bird planted there. On the other hand, if it's the latter, then how come blades of grass aren't coming out the holes along the sides of the post? Someone please help with this puzzlement.