Hey I lived in NJ for a while, in fact not too far from jackson. I would suggest trying the shore first though, Sandy hook, point pleasant etc. Even the beaches of atlantic city. Anywhere with alot of traffic usually have alot of lost coins lying around.
As for relics etc. Pick up a few copies of Wierd NJ. There are locations listed in there of weird and interesting places to go in NJ. I bet some of them would be good to find stuff on.