We know that Tantalus had many possessions, many fields and a lot of wealth.
χρῆμα - is a word that means money, wealth or just things. We might say today that he has a lot of stuff! It is a useful word which comes up a lot in other ancient Greek texts for instance in Hesiod's Works and Days he writes χρήματα ψυχὴ πέλεται . . βροτοῖσι which literally means that a man's money is his life. I like to remember this word by saying to myself that "people go into crime in order to make money".
ἀγροὺς - this word in its dictionary form is ἀγρός which means fields, land, farm or country. It is from this word that we get our word agriculture which is how I remember it.
πλουσιώτατος - in its dictionary form this word is πλούσιος and this word means wealthy. I remember this word by saying to myself that "plus" means to add and someone who is wealthy has more and more stuff.