To see mustard in a dream means success, wealth and happiness. See someone else eating mustard means jealousy or envy. To dream that you are eating mustard seeds denotes that you will regret an action.
Dream dictionary: ploughing seeds dream meanings
…To dream about a barn full of seeds and food announces future prosperity for the dreamer or, at least, it indicates that he/she is working hard to get it. If you dream that the barn is empty, dirty or neglected, then this dream indicates the opposite; i.e. that you’ll suffer hardships….
…(Dried fruits | Fresh fruits) In a dream, a sweet tasting fruit represents blessings, knowledge or money. Even a sour tasting fruit means the same when it suits the taste of the person eating it in his dream. When a sour tasting fruit does not agree with the person’s taste in the dream, then it means unlawful earnings or aggravation of his illness. Eating or drinking any by-product that is made of fruit in a dream means debts or facing challenges in a foreign land. Seeing one’s most preferred fruit in a dream represent profits earned from one’s own sweat and such profits will equal the amount of efforts exerted to earn them. A large size fruit in a dream represents earnings that are not yet free from due alms. A fruit without seeds or hull in a dream represents success and lawful earnings. Eating fruits out of season…
Usually seeds are the symbols of new ideas and chances the dreamer has.