While oilseeds receive much of the attention, tree nuts, which are technically a seed and containing oil, have gone even more gangbusters for U.S. producers in recent years. Almonds have received much of the focus as the U.S. produces nearly 80 percent of the crop and a comparable share of the global trade in the nut. But almonds have run into some controversy over the large amounts of water they require in California’s semi-arid environment. Moreover, global competition has increased with other producers expanding their output of almonds.The U.S. is far less dominant in walnuts, which have historically been an important tree nut in Asia where it is considered “brain food” since its shell is shaped like the human brain. The U.S. produces le...