Answer:
A time when they're green. A time when they're brown. But both of these times, cause me to frown. But just in between, for a very short while. They're perfect and yellow. And cause me to smile.
What is it which builds things up? Lays mountains low? Dries up lakes, and makes things grow? Cares not a whim about your passing? And is like few other things, because it is everlasting?
I am round as a bowl, deep as a tub, but all the world's water couldn't fill me up.
Different lights do make me strange, thus into different sizes I will change.
How far will a blind dog walk into a forest?
This food is a tortilla filled with cheese and sometimes chicken before being heated or cooked.