In this chapter, Nephi and his brothers, along with Laban's servant Zoram, return to the wilderness from Jerusalem.
And it came to pass that after we had come down into the wilderness unto our father. 1 Nephi 5:1a
I guess the 400+ kilometer trip was getting routine by now, because Nephi says nothing at all about it. His parents, though, were filled with joy, exceedingly glad even, to see them.
Behold, he was filled with joy, and also my mother, Sariah, was exceedingly glad, for she truly had mourned because of us. 1 Nephi 5:1b
In fact, after the boys got back, the parents just couldn't stop talking about it. After this manner of language did they speak:
And after this manner of language had my mother complained against my father. 1 Nephi 5:3
And after this manner of language did my father, Lehi, comfort my mother. 1 Nephi 5:6
And after this manner of language did she speak. 1 Nephi 5:8
After they were done speaking in that manner of language, Lehi took a look at the brass plates. They had all kinds of cool stuff written on them: the five books of Moses, the history of the Jews, and the prophecies of Jeremiah.
Lehi ... beheld that they did contain the five books of Moses ... And also a record of the Jews from the beginning, even down to the commencement of the reign of Zedekiah ... And also the prophecies which have been spoken by the mouth of Jeremiah. 1 Nephi 5:10-13
And, most important of all, the plates had Lehi's genealogy, which showed that Lehi was a descendant of Joseph. (Joseph is a really important name in the Book of Mormon. I'm not sure why.)
And it came to pass that my father, Lehi, also found upon the plates of brass a genealogy of his fathers. wherefore he knew that he was a descendant of Joseph; yea, even that Joseph who was the son of Jacob. 1 Nephi 5:14
When Lehi found out that he was a descendant of Joseph, he was filled up with the Spirit and started to prophesy about his seed, saying the plates would never perish or dim with time. (No one has seen them since.)
When my father saw all these things, he was filled with the Spirit, and began to prophesy concerning his seed -- That these plates of brass should go forth unto all nations, kindreds, tongues, and people who were of his seed. Wherefore, he said that these plates of brass should never perish; neither should they be dimmed any more by time. 1 Nephi 5:17-19a
And then he prophesied some more stuff about his seed.
And he prophesied many things concerning his seed. 1 Nephi 5:19b