hmmm, interesting finds
My first thought on that big hunk of metal is a flip down license plate holder where the gas tank would be. It looks to me like you soaked those coins together in some vinegar. Your should separate the clad and from the copper pennies before cleaning as all that copper leaches onto the silver. I know because I have done it too. we are probably all guilty. Anyway, there is a fun trick you can do with the pennies as long as they are not a valuable year. Put about a teaspoon of salt with a 1/2 cup of vinegar and soak them for a minute. Then when you take them out, dry them off and then rub a pink pencil eraser on each and they should look brand new.