Walnut
A nut shaped like a small brain in a hard shell — old food associated with knowledge and patience.
A walnut in a dream is the dream's image of food long associated with knowledge — the shape of the kernel echoes the shape of the brain, and the tradition of reading the resemblance is old. The walnut is also slow food; the tree takes years to fruit. The dream brings the walnut when something in your life — a long study, a piece of understanding that came from years of work, a patient friendship with an older person — is producing something whose shape carries the time it took. A walnut cracked open at the right moment is the dream affirming the slow yield. A walnut found rotten inside its perfect shell is the dream noting that the long process was interrupted at some point along the way, and the exterior arrived without the interior.