The sign appeared last fall in the yard of a neighbor near Walpole High School, which uses Rebels as a mascot name.
In 1994, school officials eliminated the Confederate flag as the unofficial school emblem, declaring it inappropriate and a divisive symbol of racial segregation.
The homeowner who hung the sign in his yard -- a Walpole High School student in the 1960s -- has the legal right to display it, The Boston Globe reported Tuesday.
The sign, however, made school officials so uncomfortable, a disclaimer is read to the crowds at sporting events on the school field.
"The Walpole School Committee apologized to anyone who may be offended by the private citizen who chooses to display a Confederate flag in close proximity to the Walpole High School field," the message goes. "It in no way reflects values that we support."
The homeowner, who was not publicly identified, was not available for comment, the Globe reported.