The brass Key behind the picture Frame

"I dreamed there was a small brass key taped behind a picture frame in my apartment, and I somehow knew it had been there forever even though I'd never noticed it. I don't know why I took the picture down in the first place. I just did. The key didn't fit my front door or my bedroom, but every time I tried it in a lock, I'd end up somewhere else. One door opened into my old elementary school hallway at night. Another opened into a room full of my childhood stuff, like my old bikes and toys, except everything was smaller than I remembered. I kept thinking I should call someone, but I didn't know who. At one point I found a tiny door near the ceiling and the key fit perfectly, but I couldn't reach it no matter how hard I tried. Then my mom's voice came from somewhere behind me asking if I'd found “the other one,” and I woke up before I could ask what she meant."