In verse 8, Nephi see in vision the tree of life that his father saw (see 1 Nephi 8). This passage follows:
9 And it came to pass after I had seen the tree, I said unto the Spirit: I behold thou hast shown unto me the tree which is precious above all.He is then immediately shown another vision, of a virgin "exceedingly fair and white." She is carried away in the Spirit and then bears a child. Nephi is told in verse 21: "Behold the Lamb of God."
10 And he said unto me: What desirest thou?
11 And I said unto him: To know the interpretation thereof...
Then this passage follows:
21 ...Knowest thou the meaning of the tree which thy father saw?So how is this an evidence of the authenticity of the Book of Mormon?
22 And I answered him, saying: Yea, it is the love of God, which sheddeth itself abroad in the hearts of the children of men; wherefore, it is the most desirable above all things.
23 And he spake unto me, saying: Yea, and the most joyous to the soul.
Asherah was the mother goddess of the ancient Israelites (who were polytheists prior to 586 BC according to modern archaeological discoveries), revered as a symbol of wisdom and represented by the tree. This idea was later rejected as blasphemous by the Deuteronomists who compiled the Old Testament, which is why you see references to tearing down groves in the Old Testament.
It is clear from discoveries that came after Joseph Smith that Lehi and Nephi would have been very familiar and accepting of the idea that a tree could represent a divine feminine mother of God.
For further reading, see this paper. Or this short video.
I don't see any way that Joseph Smith (or anyone on earth, for that matter) could have known this connection or its significance to Lehi and Nephi's cultural context. No rabbi would have been teaching this. So the best/only way to explain this away is total coincidence.
Consider further this connection made by Margaret Barker, a non-member biblical scholar, who studied the revelations of Joseph Smith and came to some interesting conclusions (from page 8):
The tree of life made one happy, according to the Book of Proverbs (Proverbs 3:18), but for detailed descriptions of the tree we have to rely on the noncanonical texts. Enoch described it as perfumed, with fruit like grapes (1 Enoch 32:5), and a text discovered in Egypt in 1945 described the tree as beautiful, fiery, and with fruit like white grapes. I do not know of any other source that describes the fruit as white grapes. Imagine my surprise when I read the account of Lehi’s vision of the tree whose white fruit made one happy, and the interpretation that the Virgin in Nazareth was the mother of the Son of God after the manner of the flesh (1 Nephi 11:14–23). This is the Heavenly Mother, represented by the tree of life, and then Mary and her Son on earth. This revelation to Joseph Smith was the ancient Wisdom symbolism, intact, and almost certainly as it was known in 600 bce.