Answer:
My tongue hangs out as I run over fields and streets all day. I get tied up every morning and untied at night.
I went to the woods and got it, when i got it didn’t want it, looked for it, couldn’t find it so I took it home.
I run through hills. I veer around mountains. I leap over rivers. And crawl through the forests. Step out your door to find me.
When I get closer my tail grows longer, but when I go away my tail leads the way.
As soft as silk, as white as milk, as bitter as gall, a thick green wall, and a green coat covers me all.
What is always coming but never arrives?