What does The Bust of Pallas symbolize?

it symbolizes death of his lost love lenore.

No,The Bust of Pallas is the Goddess of Wisdom. When the raven lands on the bust, it symbolizes that the raven is speaking the Word "nevermore" from wisdom rather than just a stock reply. The symbolism of The Bust of Pallas gives the narrator's anguish more intensity because the raven "wisely" utters the Word nevermore when asked about Lenore.