Everyone attaches meanings to objects, people and events that are different for each individual. Lettuce, for example, reminds you of salad is a correct statement for most people. Yet, if you spent your summers as a teenager on a lettuce farm where you experienced your first kiss, then lettuce could mean something all together different to you. Dream books can give general meanings of salad or lettuce that would suffice for many but not for all. It all depends on the individuals personal associations that cannot be taken into account by a book.
Dreams usually convey an overall impression or feeling.
If a particular object recurred throughout the dream, think of what that object means to you. For example, if you had a dream of a cat chasing a dog through the meadow as people watched, you would rate each symbol in order of importance or degree of puzzlement to you. If you found the meadow to have the most meaning, then your dream is tryingto convey something to you about your environment. If the dog being chased by the cat is perplexing to you, then the dream is trying to tell you something about your relationships and in this case that a role reversal may be occurring. How you feel about that role reversal will be determined by how you felt when you first saw the cat chase the dog.