Answer:
I build bridges of silver and crowns of gold. What am I?
The shorter I am the bigger I am.
I'm the source of all emotion but I'm caged in a white prison.
I have a small hill with seven holes.
Taken from a mine and then locked up in a wooden case. I am used by students everyday.
The sun bakes them, The hand breaks them, The foot treads on them, And the mouth tastes them. What are they?