I get a pan rattle nosie underneathe driver side for a short period of engine startup. Also here it at certain points of acceration of the vehicle.
Pan rattle noise underneath driver side on 2005 Nissan Pathfinder
Its hard to give an opinion on a noise without hearing it but this could be a damaged or deteriorated exhaust system heat shield. If the noise is only present when the engine is started from cold and goes away as the engine warms up t could be a cracked exhaust manifold or exhaust pipe, (as the exhaust warms up things expand and the noise may go away). If a noise is present on acceleration it may be an internal problem in the exhaust or catalytic converter. The problem should be easy to locate if you can duplicate the noise experienced to your mechanic.
Have been having the same problem with mine. Have stated the issue to the service people several times and they never hear anything. I hear it when I shut my driver door also.I now know it's the exhaust, because I have found two damaged rings on my exhaust. It may be the same for you.
I had the same problem. I took it in and they identified it as being a loose heat shield. He clamped it down so I'm hopeful that will fix it.