Well, if there was some hard plastic pieces, sounds like she ate something she shouldn't have. Her body is probably trying to get rid of it. Hopefully, it hasn't caused a blockage which is making her vomit. I would definately watch and make sure she goes to the bathroom too. If there is a blockage, you need to get her to a vet. It probably wouldn't hurt to call your vet and tell him/her what is going on either, especially with the plastic pieces.