Answer:
They took me from my mother's side where I was bravely bred and when to age I did become they did cut off my head. They gave to me some diet drink that often made me mad but it made peace between two kings and made two lovers glad.
I am a precious stone, as clear as a diamond. Though you can walk on water with my power, try to keep me, and I'll vanish in an hour. What am I?
I am black of eye and bright of hair. I fast into the ground and follow my lord as he races around the world. What am I?
You hold my tail while I fish for you. What am I?
My tail is long, my coat is brown. I like the country, I like the town. I can live in a house or live in a shed, and I come out to play when you are in bed. What am I?
Those with eyes bigger than their stomach will definitely leave the restaurant with one of them. It is named after a house pet as well.