I'd take a pound of modern seeds. The plants we have today are amazing in terms of productivity compared to even a century ago. And to be pragmatic, although it

I'd take a pound of modern seeds. The plants we have today are amazing in terms of productivity compared to even a century ago. And to be pragmatic, although it's fun to fantasize about being the one to start the Industrial Revolution centuries earlier, one person in ancient times is very likely to just die of disease or violence before anything grand could happen. But Farmers know what to do with seeds, and after the first harvest, the boon of plentiful crops will have spread no matter what.