My 20mth old ate a piece of a toy about the size of a peanut on friday night but i havnt seen it in his poop yet, could it b stuck?can it show in xray

Might not/doubt it: This should pass through without any fanfare by 3-5 days after ingestion.Unless you are sifting through all the poo you may not find it. Unless the item had some metallic component, it may not show up on an x-ray. In the future if he does something similar you can feed him stewed okra. The material envelops the objects and allows easier passage .