Finding where a river begins is read as a search for origins — the root of a feeling, a family story or a decision. Dream books link it to going back to where something first started.
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.