The Complete Guide to Interpreting Your Dreams

by Stearn Robinson - Tom Corbett
Although there is a good deal of difference of opinion concerning the meaning of onions in a dream, a consensus of authoritative sources leads to the conclusion that to see onions forecasts a season of ups and downs; to eat them augurs an unexpected increase in material wealth, possibly through a legacy or a lucky gamble; to peel them prophesies family trouble (especially if your eyes watered); to cook them portends the estrangement of an important friend, and to serve them warns against too much emphasis on trivial pleasures.

Gypsy Dream Dictionary

by Raymond Buckland
Different Gypsies have different things to say about onions. Generally they tie in with luck, be it good or bad.

If you dream of eating onions, some say you will be a receiver of stolen property while others say you will discover some hidden treasure. However, many Gypsies say that eating onions means you will get into a very disagreeable argument, perhaps with your own family.

To throw away onions means you will break up with your spouse or lover.

If you buy onions, you will receive an unexpected bonus.

The Complete Dream Book

by Gillian Holloway
To dream of these useful vegetables denotes a mixture of good and ill luck.

If you are eating them, you. will receive some money, recover some lost or stolen thing, or discover some hidden treasure; your sweetheart will be faithful, but of a cross temper. It also denotes attacks from thieves and a failure of crops.

If you are gathering onions, it betokens the receipt of some unexpected news of a joyful kind, the recovery of some sick person of your family» or a speedy removal from your present situation.