Small Plates of Nephi
After Nephi had begun the large plates, he was instructed by the Lord to make another set of plates to record "the ministry and the prophecies, the more plain and precious parts of them." These smaller plates were kept by Nephi's descendants until about 150 BC, when the prophet Amaleki delivered the plates to Benjamin, king of Zarahemla, who "put them with the other plates, which contained records which had been handed down by the kings" (Words of Mormon 1:10). Amaleki's last writing was to state that the small plates were full (Omni 1:30) and from this point there were no further additions to the small plates. Mormon did not abridge the small plates of Nephi, but he did include them in the records he gave to his son Moroni (Words of Mormon 1:6).
The first seven books of the Book of Mormon, from First Nephi to Omni are a translation of the small plates of Nephi. Bold text