Second years Josh Southway and Pat Keary have signed one-year deals with the Pirates while first-year scholar Jamie Lucas put pen to paper on a two-year deal.
But fellow youngsters Connor Finn and Sam Kamara have been released by the League Two side.
"All the lads who have been offered their first pro contract fully deserve this massive opportunity," head of youth Tom Curtis told the club's official website.
"This is a reflection of all the hard work put in throughout the academy system, and it is great for us all to see it paying dividends.
"Connor and Sam have made fantastic contributions, and are great personalities, and we wish them well for the future."
Manager Ward joined Matt Harrold and Michael Smith in committing his future to the club last week.