Answer:
What has roots that nobody sees, and is taller than trees. Up, up it goes, and yet it never grows.
Lots of them make up a word, And lots of words are in them. It's easy when you think about it. A while ago we stamped and mailed them.
It weighs next to nothing but no one can hold it for long. What is it?
What comes one time in today, three times in tomorrow and never in the future?
What goes up but never goes down?
When is it bad luck to see a black cat?
Easy
Animal
Difficult
Food
Funny
Kids
Logic
What am I?