A couple of posts back, I mentioned a published list of Britishisms that included eleven “words and expressions that have been common in America for as long as I can remember, and which I wouldn’t have necessarily thought of as British in origin.” I commented that initial investigation suggested only three of them seemed to be proper Britishisms. The first was “smarmy.” And the second is “full of beans.”
The OED defines the expression, which seems to derive from horse racing, as meaning “to be full of energy, and in high spirits.” The first citation is from an 1843 novel: “‘Ounds, ‘osses, and men, are in a glorious state of excitement! Full o’ beans and benevolence!”
That and all subsequent citations are from British sources. In Green’s Dictionary of Slang, all cites are from Britain or the Commonwealth until this from the American writer Leo Rosten’s 1975 novel Dear Herm: “Now he is full of beans and vinegar and with a whole new outlook on Life.” (That seems like a euphemistic switch on the roughly equivalent U.S. phrase “full of piss and vinegar.”) One earlier U.S. use of “full of beans” is in a 1938 New York Times article: “Whenever Sage, a cowboy with whom I once punched cows on the San Simon Ranch in Eastern New Mexico, felt particularly full of beans of a cool early morning….”
In any case, Google Books Ngram Viewer shows British dominance for the phrase until roughly the late 1970s, when the U.S. caught up. That was followed by a British spurt, and equivalence again in 2000, the last year for which the database has reliable data. (Note there are some false positives, for example, for references to a pot that is literally full of beans.)