In Act Four, scene three, of Shakespeare's Julius Caesar, Cassius and Brutus are arguing. Cassius calls aloud that Antony and Octavius could come and kill him.
Come, Antony, and young Octavius, come,
Revenge yourselves alone on Cassius,
For Cassius is aweary of the world:
Hated by one he loves... (IV.iii.102-105)
Then Cassius offers Brutus the same opportunity, to kill him if he wishes it by stabbing him in the heart.
There is my dagger,
And here my naked breast; within, a heart (110)
Dearer than Pluto's mine, richer than gold. (IV.iii.109-111)
Depending upon what text you refer to, Pluto is sometimes "translated" to mean "Plutus." Pluto is the Roman god of the underworld and "judge of the dead."
Plutus is the Greek god of abundance or wealth, a personification of ploutos (Greek: “riches”).
It is difficult to say which one is being referred to as Cassius is offering his dagger and his naked breast for Brutus to kill him if he so desires. If this were the case, Cassius would be conveyed to the underworld at that point, and Pluto would be an accurate reference.
However, Cassius has also mentioned the value of his heart ("...a heart / Dearer than Pluto's mine, richer than gold"), so if I had to choose one, I would select Plutus—Plutus' mine would be overflowing with abundant wealth; Cassius is saying that his heart is more valuable than such a cache of riches.