There's only one NBA player named Antawn Jamison: Antawn Cortez Jamison.  His career was pretty interesting itself:

Played for 16 seasons across 6 different teams: Golden State Warriors, Dallas Mavericks, Washington Wizards, Cleveland Cavaliers, Los Angeles Lakers, and LA Clippers.

Drafted 4th overall in 1998 by the Toronto Raptors but immediately traded to the Golden State Warriors to play with his college teammate Vince Carter.

Won the NBA Sixth Man of the Year Award in 2004 with the Dallas Mavericks.

Became a two-time NBA All-Star in 2004 and 2005 with the Washington Wizards.

Scored over 20,000 points in his career and averaged 18.5 points and 7.5 rebounds per game.

Currently works as the Director of Pro Personnel for the Washington Wizards.