I think you should toss it ... I'll send you my mailing address so you toss it the right way ....
Seriously - it sounds like tin-lined copper. As far as sticking - just grease it like any other casserole. Just a couple of things to keep in mind - it cooks faster than ceramic/Pyrex/other metals and doesn't require as much heat, so I would use it for something not requiring more than 350ºF - and check it a few minutes before the recipe time says.
Second, the tin lining is softer than other metals and can be softened, or melted, at high heats. It can also be easily scratched - so only use wood, silicone or nylon utensils ... metal spoons are a no-no.
Don't be afraid to use it! All cookware has its own particular quirks - you just have to respect them and learn how to use them.