A strange & intriguing ad... any ideas about purpose?

I just saw this local ad: "Looking for common garden weeds" which was followed by this: "Need to collect a couple of kilos of chemical free pursulane (Portulaca), Amaranth, and Chenopodium (goosefoot)."

I think it would be a bit rude to ask them why they want these and so much of each.

Does anyone want to venture a guess why someone might want this much? Maybe a huge salad for something? That's all I can think of. I'm so curious.

What's your guess?