Lisa, I'll add my commiseration to all your other friends. It is a low blow and a stinky thing to have happened. I truly hope that the people that stole them thought the flowers were going to be dug up and tossed because of the new construction. A place I once worked at dug up all the azaleas around the property and started burning them. It broke my heart and I talked with the people burning them off and asked if I could take some of the less damaged ones home with me to replant. I got a couple of trunkloads of large, beautiful George Tabor azaleas. A car dealership in Tallahassee changed hands and the 20 or so large crepe myrtles were just ripped from the ground so their roots were broken off and so damaged that they would never survive.
This still sucks and it seems like all the love and work you have poured into the garden seems somehow wasted but the lesson you are teaching the students is something that they will carry with them for life and be much better people than they could have been. Empathy is sometimes hard to teach and in this case, expensive too. My heart is with you.