Golson, 23, was the Phillies' first round selection (21st overall) in the 2004 June draft.
He spent the 2008 season at Double-A Reading in the Eastern League and was a September call-up for Philadelphia.
Golson went 0-for-6 with 2 runs scored over 6 games with the eventual World Series champions, his only major league action to date. A finalist for the U.S. Olympic team, he also participated in the MLB Futures Game at Yankee Stadium on July 13.
The right-handed batter was born and still resides in Austin.
Golson batted .282 with 13 home runs, 18 doubles, and 60 RBI in 106 games for Reading this season.
He was 23-for-28 in steal attempts for the year and was named to the Eastern League's midseason All-Star team. In a survey by Baseball America, Golson was voted most exciting player, fastest base runner, and best outfield arm by Eastern League managers.
Mayberry, 24, began the year at Frisco (AA) before earning a promotion to Oklahoma (AAA) after the first month of the season. The organization's first round draft pick in 2005 (19th overall, Stanford University), his father, John Sr., is a member of the Kansas City Royals Hall of Fame.