my daughter swallowed a $2 coin?!

Well, a $2 coin is a bit larger than a penny so it may be harder for her body to pass it. To be safe, I would call your/her doctor in the morning to get more solid advice. They may suggest that you come in, or they may suggest to let it pass on it's own. Personally, I think it'll be okay to let it pass on it's own. But if she starts experiencing any pain, especially in the abdominal region, seek medical attention immediately, as this could be a sign that the coin has perforated one or more of her organs.
Good Luck!

Nursing student.