Have you ever seen longer grass bits in your chickens' poop?
Not all, but some of the longer bits come out without being crushed by the gizzard, and even more so when they are not fed additional granite grit.
Here in Germany sauerkraut is available in every grocery store. If your usual grocery stores do not carry it, try delicatessen.
It consists of fermented cabbage.
In case the screw and staple are still located in the digestive tract, you can feed her lots of natural sauerkraut as it will wrap around the object thus preventing cuts and injuries while helping to expel the foreign objects.
I had very good experience in doing so with my dogs, after a few...