The resources and difficulties we carry in life; our past experience or karma; a burden—perhaps of nursed anger or other negative feelings—we cany, our child, if we feel parenthood a heavy load. ... A Guide to Dreams and Sleep Experiences
1- When we discover that we, or someone else, is wearing a knapsack in a dream, we are dreaming either about the difficulties we are carrying for instance, anger or jealousy or about the resources we have accumulated.
2- In Tarot imagery, the Fool carries in his knapsack the lessons he has to learn in life.
If one believes in reincarnation, the knapsack is also reputed to earn- those things one has brought forward from a previous life. These can also be the resources which one has in order to deal with problems.
3- Spiritually the knapsack suggests those qualities which are external to ourselves, and which we must learn to handle. These may be negative or positive it depends on how we handle them.... Ten Thousand Dream Dictionary