Hassell, who spent the last four seasons with the Wolves, averaged 6.7 points per game and three rebounds in 476 games. In 2006-07, he played in 76 games and averaged 6.7 points and 3.2 rebounds.
Buckner is an eight-year NBA veteran with career averages of 5.5 points and 2.9 rebounds, including two stints with Dallas along with stops in Philadelphia and Denver. Last season, Buckner averaged four points while grabbing 2.1 rebounds.
The Timberwolves open their 2007-08 training camp Saturday.