First Vision
There are multiple accounts (at least 4) of the First Vision. The accounts contradict each other, and many important details are different depending on which account you read. The only version that Joseph Smith himself wrote down was not written down until 1832, when he was 27 years old. In this version he said he was 15 so that would be 12 years after the vision supposedly happened. There is no account of him having written or even told anyone of this vision, which is strange given how important it is. The differences in the various accounts of the First Vision are significant – his age/date it occurred, his reason for seeking divine inspiration, who/how many beings appeared to him, what they said to him, etc.
Want more detail? See https://read.cesletter.org/first-vision/, https://www.ldsdiscussions.com/firstvision-overview and http://www.mormonthink.com/firstvisionweb.htm