Why would a brillow pad looking thing be in my tailpipe? We just recently got a Pontiac grand am GT which has 4 tailpipes. I have to park it on the street. Should that be in my tailpipe or is someone messing with my car?

Someone is messing with your car.  There shouldn't be anything in the tailpipe.

Was it stored?

If this car was previously stored or garaged for a long time, sometimes to keep mice from crawling up into the engine, or into the car itself, you can use brillo pads made of metal . . . They can chew through it to get to the other side. Another thing you might find in stored cars is Dryer sheets or moth balls. Mice don't like the smell of either of these . .

Of Course the idea is that the owner removes these during the driving times . . . Maybe they forgot?