I am (Eddy Vedder style)

I am evidence to prove a murderer's guilt. I am a teacher whose attitude does not reflect my salary. I am the chalk on the highbar. I am the safety net at the circus. I am the prize everyone is playing for. I am a payday. I am Mozart's pen. I am Elvis's guitar. I am a raincloud in a time of drought. I am a lost dog that's found its way home.