I just finished reading Third Nephi and was thinking about the three Nephites. I came upon this website about church folklore. This is the website:
http://theboard.byu.edu/questions/23621/
Q:
Dear 100 Hour Board,
Has any General Authorities claimed to have seen or met any of the three Nephites?
Skysee
A: Dear Skysee,
I couldn't find anything about recent GAs seeing the three Nephites; since these stories have passed firmly into the realm of Mormon folklore, it would probably behoove authority figures to keep mum on such a topic, lest they inadvertently either feed or destroy such a fruitful folklore. Basically, stories of the three Nephites are now permanently tainted with the label "folklore," and as such aren't particularly convincing faith-promoting rumors for many. It would be all to easy for skeptics to discount even three Nephites stories from General Authorities on these grounds.
(Anyone who has done better research may feel free to call me on this one. Proving the inexistence of evidence is much tricker than proving the existence of evidence.)
However, I did find several sources attesting to the belief of past prophets and GAs in the three Nephites. I'll quote a few of those accounts here.
First, a story from an early pioneer, Zina Diantha Huntington.
When Zina Diantha was eleven, the Huntington family received an unusual visitor. They treated it as a significant occurrence, but the experience assumed heightened importance when the family joined the Mormons and heard the mysterious story of the Three Nephites, ancient Americans promised by a resurrected Jesus they would live until the Second Coming. As told by Zina Diantha's daughter, Zina Young Card, the visit occurred on a cold November evening in 1832. The family had gathered for their customary scripture study followed by a musical evening with Zina Diantha playing the cello. After they had finished a piece of music, they heard a knock at the door and opened it to a man of medium height, dressed in old-fashioned clothing, and carrying a bundle under his arm. He stepped into the room and inquired, "I usually bend my steps to some sequestered vale. May I find lodging here tonight?" They pulled up a chair for him, served him some supper, and read with him a section from the New Testament. Zina Baker commented wistfully that they would like to "hear the Gospel in its fullness as explained by the Saviour. The stranger immediately took up the subject and began explaining the scriptures and quoting the sayings of the Saviour. It seemed to them that his words held a new light and were clearer than they had ever thought of before. The stranger filled them with awe and reverence, such as they had never before felt." He left the next morning.
A few years later, when Joseph Smith spoke to a group of Latter-day Saints about the Three Nephites, William recounted this visit. Joseph laid his hand on William's shoulder and said, "My dear brother, that man was one of the Three Nephites who was sent by the Lord to prepare your family to receive the restored gospel of Jesus Christ."
Second, in case you need more proof about Joseph Smith, a short excerpt from the writings of Daniel H. Ludlow:
In the 1820s the Three Nephites appeared quite regularly to the Prophet Joseph Smith...
And just a little more about Joseph Smith, from the journals of Oliver B. Huntington:
While "the camp of Zion" was on the way to Missouri in 1834 Joseph was some ways ahead of the company one day, when there was seen talking with him by the roadside a man, a stranger. When the company came up there was no person with him. When at camp that night, Heber asked the Prophet who that man was; Joseph replied it was the beloved Disciple, John, who was then on his way to the ten tribes in the north.
I have heard Joseph say that "John was among the ten tribes beyond the north pole."
The matter relating to the Three Nephites was this.
The morning that the Army of Governor Boggs' exterminating order, attempted to come into Far West; Joseph the Prophet stood with the brethren behind the breast works so hastily thrown up in the night, and remarked as they were sweeping and swarming towards the beloved city; that if they came beyond a certain place, we would upon fire upon them.
The army on, near the spot designated and on a sudden, they all turned and ran pell mell back to their camp, in great fright, declaring they saw too many thousands of soldiers to think of attacking the city.
Joseph told Brother James Bird, "that he saw between them and the mob one of the Three Nephites, with a drawn sword, before he made the remark about opening fire upon them, and when the mob had returned he saw the Three Nephites near the same place armed for battle."
The hosts that the three had with them, were undoubtedly exposed, by the power of God, to the view of the mob, being the hosts of soldiers they saw and fled from.
It's pretty clear that Joseph Smith was willing to relate stories about witnessing the three Nephites.
"Condemn me not because of mine imperfection,... but rather give thanks unto God that he hath made manifest unto you our imperfections, that ye may learn to be more wise than we have been." Mormon 9:31