Williams joined Rochdale from Stockport County in January
Plymouth Argyle have signed former Rochdale left-back Robbie Williams and ex-Aston Villa trainee Durrell Berry.
The pair, who are both free agents, are the first players to be signed by Argyle manager Peter Reid this summer.
The experienced Williams, 26, has played around 200 games in nine seasons with Barnsley, Blackpool, Huddersfield, Stockport and Rochdale.
Full-back Berry, 19, was released after being part of the Villa team which reached the 2009-10 Youth Cup Final.
Reid is also giving trials to Andy Crompton, an 18-year-old forward formerly on the books at Manchester United, and fellow striker Luke Daley, 21, who made ten appearances in all competitions for Norwich City the season before last.