I have been playing around with some flowing formations lately which I have always avoided because they deal with the dreaded Math. Luckily my friend at Dyleeo helped me out with really understanding how to use sin and cos for smooth movement.
This first version was a test of leaves moving across the screen: leafFormation_v2
The section version is leaves moving in place (as if the camera was following them): leafFormation_v3
download source (both versions)