The United States captured a famous London Sevens success after accounting for hosts England in the semi-final and Australia in the final, while Fiji won the HSBC Sevens World Series.
England had secured a sevens berth for Great Britain at next year's Rio Olympics after reaching the quarter-finals on Saturday, and they extended their successful tournament by beating New Zealand in the last eight.
But they were beaten 43-12 by the Americans, with two tries each from Madison Hughes, Carlin Isles and Perry Baker, and went on to lose 26-12 in the third-placed play-off against Fiji.
The States, though, had more celebrations to come as they beat Australia 45-22 in the final, with Danny Barrett and Maka Unufe each crossing twice and player of the tournament Hughes adding another nine points.
Hughes told worldrugby.org: "It is an absolutely incredible feeling, I remember coming to this tournament as a boy watching from the stands hoping that I could play in it some day.
"There is so much more to come, thank you very much for a phenomenal tournament and weekend."
Coach Mike Friday added: "It is amazing, credit to those boys the 12 of them have been absolutely fantastic."
Fiji wrapped up the series title at the moment they beat South Africa in their quarter-final and coach Ben Ryan said: " The boys were very overly emotional in the changing room and I had to control them a bit and remind them to start smiling and that this is supposed to be fun.
"We've won 29 out of our last 30 games so we are on a pretty hot streak and I've got a great team around me."
New Zealand regrouped to win the Plate competition, beating South Africa 26-14, and also had the consolation of Olympic qualification.
Captain DJ Forbes said: "It was probably an awesome game to watch but it was really hard to play in. Against a good South African side, I guess we can hold our heads high.
"It's hugely disappiointing to finish third overall (in the series) but that's the way sevens is going - any team can win on it's day. We achieved one of our goals though qualifying for Rio."