By looking at the trends in American food consumption over the last 40-some years, what we eat most often becomes truly clear. In the graph below, one can see that the American diet has been largely dominated (and without might change) by the consumption of white and whole wheat flowers over any other grain. This may have something to do with the idealization of wheat as the "European" or "sophisticated grain" - especially in comparison to something like corn.
The graph below shows the relative changes in the consumption of different grains since 1970. I removed the data for white and whole wheat flour from this graph because it far exceeded the other grains (making it difficult to see clearly the trends of the other data sets), and because it remained fairly consistent over time. So, from this visualization one can glean the significant increase in the consumption of rice and corn hominy and grits over the past 4 decades (the other grains have remained fairly consistent). One speculation I have is that rice consumption has increased because Americans have embraced its versatility as a gluten-friendly substitute, and have adopted the cuisines of cultures that use this grain more often.