Answer:
I am the only thing that always tells the truth. I show off everything that I see. I come in all shapes and sizes. What am I?
Everyone in the world needs me. They generously give me but never take me. What am I?
I am perfect with a head perfect without a head; Perfect with a tail perfect without a tail; Perfect with either neither or both.
Brown I am and much admired. Many horses have I tried. Tire a horse and worry a man, tell me this riddle if you can. What am I?
I'm a word that's hardly there. Take away my start and I'm an herbal flair. What am I?
No matter how little or how much you use me, you change me every month.