Also look for loose brake pads and broken anti-sway bar bushings. Loose brake pads will quiet down with just a little pressure on the brake pedal.
You can also hang on the bottom of the car while a helper drives it on bumpy roads, but here's a better suggestion!
There is a tool you might be able to borrow or rent from an auto parts store that borrows them called the "Chassis Ear". It is a set of six microphones, a switch box, and headphones. You clip the microphones to suspect points, then drive around while listening with the headphones. You can move the microphones around to zero in on the source of the noise. Be aware that many mechanics have never seen or even heard of this tool. Suspension and alignment mechanics use it to find rattles, squeaks, and other noises.