Ebner, who helped New England Patriots triumph in Super Bowl XLIX, has taken time out from his NFL career to join up with the Eagles squad ahead of August's Rio Games.
"Growing up playing rugby, you don't have the opportunity to play in the Olympics," the 27-year-old told reporters.
"The best thing you could get to really was the World Cup because rugby wasn't in the Olympics.
"To be a part of something I watched growing up and that has as much tradition as the Olympics ... that comes around once in a lifetime for some people. The idea to potentially be a part of something like that is humbling and it would be amazing."
A decade ago, aged 17, he was the youngest player in U.S sevens history, and starred for 15-a-side teams at international age-grade tournaments.
However, he started playing football at the end of his college days and switched sports after being drafted by the Patriots in 2012.
Ebner, a defensive back, was given permission by the Patriots to take time out to attend training at the U.S. Olympic training center in Chula Vista, California.
He was a free agent, but received a new two-year deal on Tuesday.
Ebner will return to the NFL after sevens makes its Olympic debut in Brazil -- or earlier if he fails to win a spot in the squad.
"I am absolutely not guaranteed a spot," he said. "I have to try out for the team like anybody else and I have to earn a spot like anybody. I'm just lucky to even have the opportunity to even try."
Ebner has kept in touch with his former rugby coaches since moving to NFL, and says he has been watching the competition on the sevens circuit.
USA Rugby performance director Alex Magleby is looking forward to reuniting with Ebner.
"Nate was a skilled, tough leader as he progressed through our national age-grade teams," Magleby said.
"His performances at the College Rugby Championship for Ohio State showed his talent, and anyone who watches the NFL can see his athleticism and work-ethic on display for the Patriots.
"He will be up against it in an already competitive player pool for Rio, but knowing Nate, he will relish in that challenge and will work hard to bring out the best in himself and his U.S. teammates."