Those cans were for spikes. Where you find them, you can often find a few unused spikes, which I like to use to weight a car that needs it, if there’s enough room. They are easier to deal with than the old worn and well rusted ones; and I think it’s a more appropriate weight for a train than a piece of lead.
Those spikes are really heavy, even the older smaller ones. Surprised you would use that much weight for a car.
I thought the most interesting portions of the scrap heap were the switch stand parts and point rails, along with the track worker’s hand in the first photo.
Dave, I have used whole spikes for whistle-less tenders, baggage cars, and express cars, which I know will be at the front of the train. In other situations where I don’t need or want that much weight, I cut them up.