You can make money by collecting items on the ground but kids can pick them up only.

I think you mean how to get extra tech points, John.

There are no collectibles in VV1. The only thing kids can pick up in VV1 is mushrooms (which produce food).

The only way you can make actual money value is puzzle 16, if I'm correct.

Puzzle 16? I don't thing so, halidog.
In VV1 the only manner to make tech points is to put villagers at the research table. The more they are skilled, the more they are efficient. And in 2x speed, it goes faster but they become older faster too!

I was thinking money, the treasure chest.

Oh! Ok! But it's not (highlight the following for SPOILER) the puzzle 16 which is the cave! The treasure is the puzzle 15! (end of spoiler)

Whoops. My bad. I forgot it

It's important to make sure you check your facts before giving answers to people. Most of this thread is misinformation.