First thing's first, they are Steel Cans and surely worth a whole lot of than Aluminum and tins. Just hire a trailer, collect these steel cans and sell them out, they will surely help you to make some big bucks (you don't need to clean them either) and for the rest of them, just hire some part time teenager to clean them. My friend you are surely going to make huge bucks via that, you are very lucky that you are getting this for free.