oh my gosh...that's nuts. take it to one of those exchange stores! I'm not sure if you have one in your area but we have this store called kids kaboodle here and it's basically like a trade store for new and gently used baby toys, clothes, furniture etc you take in your stuff and they give you store credit!
Since you have all boy stuff I would go buy a girl outfit or two, nothing fancy, just in case you do have a girl and you need an outfit to take her home in.