What do the 3 roses represent at Poe's grave?

Since no one knows who left those three roses, it is impossible to tell, but it is speculated that the three roses represent the three people buried in Poe's current grave: Edgar Allan Poe, Virginia Eliza Clemm Poe, and Maria Poe Clemm. By the way, did you know that the roses and cognac were left at the back of the cemetery at Poe's original grave site?