What are these other plates? They are the small plates of Nephi which constitute 1st and 2nd Nephi. See the explanation of the different plates of the Book of Mormon as found just before the table of contents. It is important to understand that Nephi does not begin the record we have been reading until 30 years after his family left Jerusalem (v. 28). Therefore, Nephi is writing his history more as his memoirs than as his daily journal. This is useful because it allows him to leave out the unnecessary details of the journey through the wilderness and focus, as he does, on the plain and precious truths of the Spirit.