Wearing a graduation gown is read as taking on the dignity of an accomplishment. Dream books link it to a formal change of status, and to how you feel stepping into a role you have earned.
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.