What Am I Riddles

Question: A man travels by wagon,
brings joy each evening,
but depression by the morning.

Who is he?

Question: I plow and plow, but never sow.

What am I?

Question: I attach to your hip and I sing all day.
All I want to do is play.

Question: Thirty white horses stand on a red hill,
First they champ,
Then they stamp,
Then they stand still.

What are they?

Question: I have roots that nobody sees,
I'm taller than any trees,
up and up I go,
but I never grow?

What am I?