MOORE, Okla. — Students from a suburban Oklahoma City elementary school destroyed by this week’s tornado reunited with their teachers Thursday and collected whatever could be salvaged from the ruins.Some children carried thank-you cards. A first-grader was eager to see her favorite gym teacher and for a chance to say goodbye for the school year. It was one of many difficult goodbyes for the city of Moore. Family and friends attended the funeral of a 9-year-old girl who died at Plaza Towers Elementary School — the first since Monday’s storm, which killed 24 people. Students who survived the storm’s onslaught at the school and those whose parents had pulled them out of class just before it hit gathered with their teachers at another Moore school that wasn’t damaged. Seven children died at Plaza Towers.Authorities kept journalists at a distance, but Cheryle Dixon, a grandmother of first-grader Crisily Dixon, talked to a reporter about how hard it was for the little girl.