Teacher accepting a gift from the students

A teacher working in a Qur’aan memorization school which belongs to al-Jamaa’ah al-Khayriyyah li Tahfeez al-Qur’aan il-Kareem (Charitable organization for memorization of the Qur’aan) does not receive any payment for her teaching. At the end of the school year, after the certificates have been given to the students, they may give her a gift of gold or something similar. What is the ruling on her accepting this gift? Refusing the gift would break her students’ hearts and upset them, especially since she has given gifts to them.