In Genesis's Noah's Ark story, the dove returned with an olive leaf after the floodwaters receded. Noah sent the dove from the ark to discover whether the waters had gone down from the earth.
The first release of the dove produced no sign, and Noah waited before sending it again. On its second return, the dove carried a freshly plucked olive leaf, showing that vegetation had become visible. A later release produced no return, which Noah interpreted as evidence that the land was becoming habitable.
The olive branch later became a widely recognized symbol of peace, although Genesis's immediate purpose is practical: it signals the changing condition of the world after the flood. The story names an olive leaf specifically, not a generic branch or another kind of plant.