Answer:
Never ahead, ever behind, yet flying swiftly past, for a child, I last forever, for adults, I'm gone too fast.
you can throw me away but I will always be coming back
I am flora not fauna. I am foliage not trees. I am shrubbery not grass.
I am a shimmering field that reaches far. Yet I have no tracks and am crossed without paths.
I am the place to turn when nature calls.
When is it bad luck to see a black cat?