In 1906 Stanford and California universities switched from American football to rugby union. Both the 1905-06 All Blacks and the 1908-09 Wallabies played matches in California on their way back home from their European tours, and an American Universities team had toured down under in 1909. Walter Camp, known as the 'Father of American football' was not impressed, as he made clear in a 1911 article:
A first class Australian league team or a team from the Northern Union such as journeyed to Australia last summer from England would outpass the Californians in many ways. Of course, in these Northern Union teams lost time is paid for, which although it does not rate the players as regular professionals, detracts from their amateur standing.
The Northern Union game, especially in Lancashire and Yorkshire, would be a revelation to many of those who have merely seen the more mediocre play. The men who form these teams are of excellent physique, strong and powerful, putting up a hard, vigorous game with tackling that is earnest enough to be severe. The business is business far beyond the notion of those who have never seen it and is rendered even more strenuous by the fact that all the games are in competitive league series. (‘Rugby Football In America’, Outing Magazine, 57 [March 1911], p. 710.)
The experiment with union didn't last. By 1919 Cal, Stanford and the other schools that followed them had gone back to the gridiron game. For more on Walter Camp, the origins of American football and its relationship to rugby, take a look at my article on the origins of the gridiron game, Unexceptional Exceptionalism.