Answer:
You seek it out, when your hunger is ripe. It sits on four legs, and smokes a pipe.
I grow for a surface, even if you cut me. I continue to grow even after death.
I am round as a bowl, deep as a tub, but all the world's water couldn't fill me up.
A precious stone, as clear as diamond. Seek it out whilst the sun's near the horizon. Though you can walk on water with its power, Try to keep it, and it'll vanish within an hour.
A word I know, six letters it contains. Subtract just one and twelve remains.
They are many and one, they wave and they drum, Used to cover a state, they go with you everywhere.