I don't think he gets it

See all these pine cones? They used to be in someone else's yard.

Here's how they got in our yard.

Joshua had one of his cousins over to play last week, and they asked me if they could take the wagon down the street a ways. Sure, said I, thinking they wanted to pull each other.

I checked on them a little while later and saw them a few houses away with pine cones in the wagon. Unfortunately, I did not give it much thought; I had primarily been confirming their whereabouts.

Some time later they came in the house, whereupon Josh and I had the following conversation:

J: Mom, you should see how many pine cones John and I collected.

Me: Really? From where?

J: Down the street. Mom, can we have some money for doing that?

Me: Where are the pine cones now?

J, pointing out our window: Right out there.

Me: In our yard??!

J: Yes. So, will you pay us?

Me: Let me see if I understand this. You want me to pay you for taking pine cones that WERE in someone else's yard and PUTTING them in our yard so now WE have a giant pine cone mess we did not have before?

J: Um . . . yeah?

Me: No.

J: Well, if we clean it up, then will you pay us?