Benjamin was the twelfth son of Jacob, by his wife Rachel who died at Benjamin's birth.  After Jacob was told that his son Joseph was dead -- although he had actually been sold into slavery -- Benjamin became his father's favorite.  Benjamin accompanied his brothers to Egypt to buy food during a famine.  There they unknowingly encountered Joseph who had become a high-ranking official.  After secretly having a cup placed in Benjamin's sack, Joseph charged that Benjamin was a thief.  When one of the brothers offered to go to prison in place of Benjamin, Joseph revealed his true identity.  Benjamin gave his name to a tribe that settled in central Palestine.

Gen 43:1-34 - Benjamin is taken to Egypt
Gen 44:1-13 - Joseph's cup placed in Benjamin's sack