Many Quakers also refuse to pledge allegiance to the flag. I can't say this is an official doctrine of the Quakers, because Quakers don't have any official doctrines or creeds. There probably are some Quaker kids who DO say the Pledge, or go through the motions, just because they don't want to make a fuss or stand out from the crowd, and I don't think Quakers would condemn them for doing it, but I think they would support anyone who refused to say the Pledge.

See Friends Statements on the Pledge of Allegiance