Answer:
A white field, and when it is plowed, its soil is black.
They live only in stories, taller than three storeys.
Do this to your gifts to make them festive
What is really easy to get into but really hard to get out of
A locked sphere without hinges or key. Break me open and golden treasures you'll see
Before I grow I'm small. When I'm old I grow tall. When I die I give a mighty fall.