Folly was signed by both Gordon Strachan and Paul Sturrock
Aberdeen will have five more potential new signings in their squad for their weekend friendlies against Fraserburgh and Peterhead.
Midfielders Yoann Folly and Adnan Ahmed, internationals with Togo and Pakistan respectively, are among the trialists hoping to win contracts.
Ex-Charlton player Grant Basey and ex-Huddersfield man Robbie Williams are options for the left side of defence.
Jeff Smith, most recently with Darlington, is a left midfielder.
They will join 18-year-old former West Ham United midfielder Conor Okus, whose trial with the Dons has been extended, in Mark McGhee's side.
Aberdeen play Highland League outfit Fraserburgh at 1500 BST Saturday and Second Division side Peterhead 23 hours later.
Clockwise: Ahmed, Basey, Williams and Smith are out to impress
The left side of McGhee's team is in need of new recruits following the departure of Charlie Mulgrew to Celtic and Davide Grassi to Sorrento Calcio after both rejected new contracts.
Defender Basey, a Wales Under-21 international who had a loan spell with Brentford in 2007, made 22 appearances for League One outfit Charlton last season after the 21-year-old emerged from the London club's youth team.
Williams, who can play at both full-back or midfield, came through the ranks at Barnsley and has played for Huddersfield Town for the last three seasons.
The 25-year-old made 22 appearances last season but was left out of the side for most of the latter part of the season as the Terriers missed out on promotion to the Championship after losing in the play-offs.
Left midfielder Smith began his career with Hartlepool United then joined Bishop Auckland before moving to Bolton Wanderers.
However, he made only two appearances for the Premier League outfit and had loan spells with Macclesfield Town, Scunthorpe United, Rochdale and Preston North End before joining Port Vale.
After three seasons, the 30-year-old moved to Carlisle United for two years and spent last season with Darlington in League Two.
The 26-year-old Ahmed, who was a trainee with Manchester United, played for Ferencvaros in the Hungarian top flight last season and has been capped 13 times for Pakistan, playing in last year's South Asian Football Federation Cup.
He left Old Trafford for a three-year spell with Huddersfield in 2004 and suffered a lack of first-team opportunities with his next club, Tranmere Rovers, who farmed him out on loan to Mansfield Town and Port Vale, before he won a two-year deal with Ferencvaros last year.
Folly, who played for France at youth level then became a senior international with Togo, is a 25-year-old defensive midfielder who started his career at St Etienne before being signed by Gordon Strachan for Southampton for £250,000 in 2003.
He had loan spells with Nottingham Forest, Preston North End and Sheffield Wednesday before winning a permanent move to the Owls, then managed by Paul Sturrock.
Sturrock signed him again, for £200,000, after the Scot moved to Plymouth Argyle in 2008.
However, Folly fell out of favour last season under new manager Paul Mortimer and had a spell on loan to Dagenham and Redbridge before being released in the summer.
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