The jack-in-the-box is read as surprise and pent-up energy waiting to burst out. Tradition links it to feelings kept under a lid until they spring free.
Does the traditional reading fit your dream, or did it mean something else to you?
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.