I think any of these would work with Pierce, but my favorites are Graham and Emmett.
Other ideas:
Anders
Arthur
Austin
Callan
Cameron
Carter
Charles
Clark
Cole
Colin
Dwight
Jack
Lewis
Lincoln
Logan
Oliver
Rafe
Reid
Ryan
Sawyer
Scott
Shane
Spencer
Steele
Tripp
Walter
Warren
William
Winston
Wyatt
Zachary