Feel her crop in the morning before she has the chance to eat. If you can feel the marble in there then you need to try to get it out and that means up over. If it gets into her gizzard it may be fatal and if it sits in her crop for any length of time it will block the outlet and cause problems like impaction or slow/sour crop. I would try to vomit it out by inverting her and massaging it towards her beak, but this is a risky process as she could aspirate any liquid that comes up. The risk is not huge but it can happen and you need to offset that against the risk of not getting it out. If you are unable to get it out by massage and/or vomiting, surgery would be the next option. I have done crop surgery twice to clear an impaction and it is not overly complicated. There are You Tube videos which show you how. I found closing up with super glue worked really well. If you don't feel able to do it yourself, then, assuming you have confirmed by palpitation that the marble is definitely in there, then you need to seek veterinary assistance or be prepared to lose the bird.