To dream of a garage sale indicates a sudden emotional clearing leading to a sense of clarity and freedom.
To feel regretful about selling an object in your dream suggests that you may not be ready to completely heal from a recent emotional issue but that you will have the energy and the courage for a full healing in the near future.
[1]To dream about a yard sale suggests that you are learning from your past experiences and making productive use of the lessons and skills you have learned.
[2]Literal sale; bargain
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