And it came to pass that we did begin to till the earth, and we began to plant seeds; yea, we did put all our seeds into the earth, which we had brought from the land of Jerusalem. And it came to pass that they did grow exceedingly; wherefore, we were blessed in abundance. And it came to pass that we did find upon the land of promise, as we journeyed in the wilderness, that there were beasts in the forests of every kind, both the cow and the ox, and the ass and the horse, and the goat and the wild goat, and all manner of wild animals, which were for the use of men. And we did find all manner of ore, both of gold, and of silver, and of copper.At first, it might seem as though Nephi is telling us this as part of the story, i.e. describing what they found upon arriving in the promised land. But remember, these small plates on which he is writing were reserved for "the things of God ... that I may persuade men to come unto the God of Abraham ... Wherefore, I shall give commandment unto my seed, that they shall not occupy these plates with things which are not of worth unto the children of men" (1 Nephi 6:3-6).
So, what is the purpose of him taking up space on the plates to tell us these things? He says his intent is to "persuade men to come unto the God of Abraham," so how does telling us that he planted seeds which "did grow exceedingly" accomplish that?
It fits in perfectly if he's talking to Mesoamericans, because they believed their nature gods were necessary for making crops grow and bringing useful things from the earth. So, Nephi tells them that it is because of his God, the God of Abraham, that he was "blessed in abundance."