This Bible contradiction is from the Skeptic's Annotated Bible.
Jesse had eight sons.
1 Samuel 16:10-11 View context
Again, Jesse made seven of his sons to pass before Samuel. And Samuel said unto Jesse, The LORD hath not chosen these.
And Samuel said unto Jesse, Are here all [thy] children? And he said, There remaineth yet the youngest, and, behold, he keepeth the sheep. And Samuel said unto Jesse, Send and fetch him: for we will not sit down till he come hither.
1 Samuel 17:12 View context
Now David [was] the son of that Ephrathite of Beth-lehem-judah, whose name [was] Jesse; and he had eight sons: and the man went among men [for] an old man in the days of Saul.
Jesse had seven sons.
1 Chronicles 2:13-15 View context
And Jesse begat his firstborn Eliab, and Abinadab the second, and Shimma the third,
Nethaneel the fourth, Raddai the fifth,
Ozem the sixth, David the seventh: