Halachic authorities state, based on the words of the Alter Rebbe, (4:2),”Regarding the evil in the morning before ritual hand-washing, (Netilas Yadayim,) one may not touch food,” but small children are allowed to. So just as it is permissible for a small child to eat before having washed his hands, it is permissible to use food that was placed under a child’s bed. The evil spirit rests only because of holiness, and the G-dly soul finishes entering the body at the age of Bar/Bat Mitzva. It is also permissible to use food touched by a non-Jew, and by a child who has not yet reached Bar/Bat Mitzvah but did not yet do the ritual handwashing.