Help!!!

I was involved in an accident at the end of last year and the car was hit from behind. Consequently I had the tow bar removed from the car and ever since at low speeds I can hear an annoying rattling sound from the rear of the car. The rattling sound can best be described as: A golf ball being shaken around in a metal box under the back seat Has anyone else experienced this.

Regards,
Peter McGowan.

PS: I have checked.