Nail
A small metal fastener driven into wood — a tiny piece that holds larger pieces together.
A nail in a dream is the dream's image of a tiny piece that holds larger pieces together. The nail is unimpressive; what depends on it is not. The dream brings the nail when something in your life — a small commitment, a minor agreement, a passing kindness — is currently doing the work of joining larger structures. A nail driven cleanly into wood is the dream affirming the small fastening. A nail bent over by the hammer, refusing to go in straight, is the dream noting that the small joining was attempted in haste, and the structure depending on it is going to wobble.