Descriptors of visual field dynamics are not too generic, and are usually related to the context.
If you want to play on the abundant or vital nature of a field of grains, gyrating is a term you might consider.
It is both a technical descriptor (the top of the grass is gyrating since it's stalk is rooted in one place at the ground), and the word alludes to human dance, which are part of mating ritual.
You may not think of it as gyrating, but if you watch tall grasses you will see that the motion is never "back and forth" — even though this may be how our mind idealizes or simplifies the memory. Look also at lemniscate curves to see what motions the grass-tops can follow.