Grinding noise under 35mph

For a week my 2004 Cavalier has been making a loud grinding noise. Like steel being draged down the street. When I get on a freeway it doesnt do it anymore but when I was driving today on side streets going from 10 mph out of my apt complex to 35-40 on the streets it still was doing it. its pretty loud and i have a warranty on it but does anyone know what it could be?

It sounds like it is coming from underneath my car.

Look and make sure its nothing hanging from the under of the car, could be a muffler off its bracket or a piece of anything dragging on the ground, check it out..

Could be Jimmy Hoffa under there.