Isabella, or the Pot of Basil (1818) is a narrative poem by John Keats, adapted from a story in Boccaccio's Decameron (IV, 5). It tells the tale of a young woman whose family intend to marry her to "some high noble and his olive trees", but who falls for Lorenzo, one of her brothers' employees. When the brothers learn of this they murder Lorenzo and bury his body. His ghost informs Isabella in a dream. She exhumes the body and buries the head in a pot of basil which she tends obsessively, while pining away
Isabella's brothers slay her lover: he appears to her in a dream, and shows her where he is buried: she privily disinters the head, and sets it in a pot of basil, whereon she daily weeps a great while. The pot being taken from her by her brothers, she dies not long after.
you can read the poem (which is lengthy here http://www.bartleby.com/126/38.html