I was in an Asian History class when I was taught this. The teacher called it the Green Sprouts Law, but I can't find any verification and I no longer have my texts from that class. Is this true? Can someone verify it? Mahalo.
Could you provide any more information on this that might help clear things up? Is it possible you're mis-remembering?
The only Green Sprouts Law (青苗法, page in Chinese) with which I'm familiar was not a law about food waste but rather loans from the government given to farmers during the Tang/Song period. See also The History of Ancient Chinese Economic Thought.