Are these tenses correct?

Hi. Please help. Let's say someone is trying to retell a folktale he read or heard to a kid. What has expired in the folktale is that an old man has told his children that he buried some treasure in the ground and want them to get it out (dig it up) when he passes away, but the children find nothing after hard digging. But instead, after all that tilling the ground, they find plump grapes hanging on the trees. Could one of the children say this? Which is correct, the verbs in the sentence or the ones in parentheses? Thank you in advance.

(looking at all the plump grapes)
Wow. Dad was right. There is treasure here after all. But it wasn't (isn't?) in the gound but was (is?) on the trees. Let's go and sell them.