Is it permissible to hold a simple ceremony and honor a teacher with a shield or gifts (flowers and chocolate) to celebrate her obtaining a patent?

There is no harm in students honoring their teacher with gifts as an encouragement and in return for her kindness, as long as the purpose is not bribery for favoritism in exams or the like. Bribery is not permissible because it is given on condition of assistance, not as a sign of honor.