TIL that the tumbleweeds commonly found in the American West are Russian thistle. They are an invasive species from Asia that adapted well to the dry, open landscapes of the western U.S.
It's kind of funny, I think, that a plant so closely associated with America is actually not native at all.
Sure, but the same applies to so many foods in so many cultures. What was Italian food like before they had access to tomatoes? Eastern, Central European, or Irish before potatoes? Chinese, Southeast Asian, or Korean before they had chili peppers?
Now each of those countries have dishes we associate with them but which use those non-native ingredients.
I think that's because British food we commonly see as awful stems from food rationing that went on during and after WWII, as far as I know well in the 1970s
That seems like a poor excuse, every country experienced rationing and they didn't revert to awful food. There's even a few dishes like fried spam and ramen that are actually pretty good.
American cuisine also suffered dramatically in the post-war period due to a reliance on, for example, canned vegetables. A whole generation or two (boomers and Gen X) grew up not knowing what spices are, practically.