If I swallowed a watermelon seed one would grow in my stomach.
My uncle had us believing that if we poured salt on a birds tail it couldn't fly and we could then catch it (a ploy to keep us all busy!).
The best is my husbands memory ... they were not wealthy. Mom told him he could have either buttered bread, or bread with margarine and jam - but never butter AND jam. Husband thought it was because the two together was poisonous!!