We tend to find what is of interest to us at the time & thats key, as you learn what sells with value you will find more, for now you are probably missing out on the metals.
So when you see a bunch of cooking pots in the trash grab them take handles off, now you have 4 to 5 lb AL @ .50 Metal finds are not to be looked down upon for the small sums as yearly the sums for copper AL SS Brass will add up.