Edgar, captain of Canada's Under-20 team, underwent hernia surgery at the end of the campaign, and is now working his way towards full fitness.
"It's good to be back, and after last season, you want to be involved in the first team, week-in, week-out.
"The gaffer gave me my chance last season and it's great to be around him."
Edgar, the son of former Magpies goalkeeper Eddie, made his name at St James' Park as a teenager with a famous equaliser against Manchester United in January last year.
He has had to remain patient both at club and international level, but had been told he is in consideration for his country's forthcoming World Cup qualifiers.
He said: "I have been on the bench for them for the last two seasons, but I feel I have what it takes and will have to take my chance."