Anything is possible. The complexity of the task depends on how realistic you expect it to be.
At one end, a very simple, but not very realistic, method would be to use a slow turbulent displacement.
At the other end, for a more realistic result you would have to cut out some flowers, turn them into 3D layers that cover the entire field and do an overall animation that would sway the entire field based on their 3D positions. You could do that in AE with expressions or use a plug-in like Trapcode Form to accomplish this.
This ( Particle Illusion 3.0 http://www.wondertouch.com/pillusion3.asp )can render out moving grass and other elements that you can then use to comp over the photograph and give the illusion of movement in the field of flowers.