Flat feet are read as being firmly, even heavily, grounded — steady but slow to spring. Some dream books see in them a feeling of being unable to leave the ground of a situation.
Has this come up in your dreams before? What was going on in your life then?
My Cosmic Code has a private dream journal. Write a dream down and the app picks out the symbols in it, shows what dream books say about them and, over time, which words recur across your entries. The journal is stored on your device only.