Hello, I'm Dr. Deb and will do my best to help with this concern about your cat.
In most cases, our pets will be fine if they eat something which they shouldn't, but when they do, I don't advise trying to make cats vomit since the risk of aspiration is too high (unlike for dogs).
For the sake of argument, if she did eat something which might cause issues, the following are the most commonly seen symptoms:
1. vomiting which often is seen within 30 minutes or so after ingestion of certain drugs or plants. If an obstruction develops, then nausea might not be seen for a day or perhaps a little longer.
2. diarrhea, usually within 12-24 hours.
3. loss of appetite...again, usually secondary to an obstruction
4. lethargy or decreased energy which might be seen today or over the next day or so
5. possibly abdominal pain if an obstruction develops
6. On the off chance that she found an otc medication, then balance issues might also be seen or trembling/twitching although the range of symptoms vary quite widely depending on the amount and drug ingested.
At this point, I'd continue to monitor her for any of the symptoms I mentioned; should they develop, then a vet visit would be wise.
I hope this helps, Deb