Answer:
Always old, sometimes new. Never sad, sometimes blue. Never empty, sometimes full. Never pushes, always pulls.
Both old people and owls are said to be possessing this trait
I grow where no flower grows, where no light touches the walls, up or down, that I don't care, was here before people were.
You eat something you neither plant nor plow. It is the son of water, but if water touches it, it dies.
I can sizzle like bacon, I am made with an egg. I have plenty of backbone, but lack a good leg. I peel layers like onions, but still remain whole. I can be long, like a flagpole, yet fit in a hole.
Black we are and much admired. Many seek us if they are tired. We tire the horse, and comfort man, and turn White when we've fulfilled your plan.