When I first started using Dynamo a few months ago, one of the first definitions I attempted was one that was shared by Jostein Olsen almost exactly a year ago, showing how you could place trees randomly within a polygon area.
This is an excellent concept for placing any sort of plantings in a naturalized way.
After seeing the FamilyInstance.SetRotation node in Dynamo, I wanted to figure out how to randomly rotate elements. There are typically not many elements that you would want to rotate randomly, but it can be done to plantings to make them appear more naturalistic in renderings.
And if you are assigning a random rotation to your plantings, then it would also be useful to randomize their height (within a specified range).