Cromniomancy. Divination by onions. Work in progress today by Julie Kwiatkowski Schuler.
Cromniomancy was usually done by inscribing “yes” or “no” on onions, then planting and asking your question of them to see which one would sprout first. That would be your answer. If it was a question of suitors, one would inscribe the name of possible lovers, one to each onion, then whichever one sprouted first was your true intended.