Wheat, the world-feeding crop whose shortage was Pharaoh’s nightmare, is now at such a global surplus that last month its price was less than two-thirds its level in 2008. Having rebounded in recent days to $4.05 per bushel from $3.62 last month, one might think that the commodity, which last June cost $5.07 per bushel and in February 2008 peaked at $11.94 …