Civic Rattling when idling or reverse

I have a 2001 Civic EX. It has recently started a rattling noise. The rattling comes and goes. I notice most I first start my car and am in reverse out of a parking space. I also notice it at stop lights or when I am driving really slowly. Any ideas?

It could be one of the hangers or heat sheilds from your exhaust system, this is often a cause of rattling comming from under the carriage. Generally it is not dangerous, unless something falls off, so you should get it put up on a lift and checked out soon.