Inside OnDragStart use event.setData("text", uniqueDragId); where uniqueDragId is a unique drag Id in your application eg "1" or "draggable:1" etc
Then inside OnDrop
test event.getData("text"); to determine if it is equal to "1" or whatever.
To get the actual text you are trying to "drop" you reference the object that you know uses the drag Id of "1" and get the text directly from it.
Therefore this whole approach doesn't really drag anything, it just uses the drag metaphor to give your "onDrop" code an id.