The actual smell of rain comes from plants. When plants are in drought they produce oils in replacement for waters. When the time comes and it finally starts raining the plants get their needed water and they release these oils in the air and the smell of that oil is what we call smell of rain
If I were in the Hunger Games I would use one of the parachutes and gift containers and put all kinds of poisonous berries in them and then climb trees and send them down to unsuspecting tributes. Oh, you thought you were getting a nice fruit salad? Think again. POISON.