A ball of yarn is read as potential not yet given shape, and as the long thread of a story. Tangled yarn is traditionally taken as confused thoughts or a complicated situation.
When this appeared in your dream, what were you feeling?
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.