What is this plant with upright leaves on a single stalk?

I've been trying to identify this plant with upright leaves on a single stalk. They make an unforgettable rustling noise when you walk through a patch of them. When I observed them they were in the 6-inch- to 20-inch-tall range.

 

Can you guess/recall the length of the leaves?

 

I believe the leaves were around one inch to one-and-one-half inch long. I'm leaning toward 1 and 1/2 inch long, but it has been several years and I saw them only once in a pasture. The cows ate them the next day.

 

Well, I've looked through the Brassicaceae of Florida, and I have either missed a match or I'm in the wrong family. Can you describe the environment a bit -- is this a natural area (state park or preserve?) or a urban/degraded area?

 

It is a cow pasture/sometimes-rotated-crop field next to my house. When I took the picture, the field had lain fallow. It was full of weeds and wildflowers, both noxious and otherwise.

 

Papery stipules and probably, ochrea - I'd think Polygonaceae.

 

Thank you so much for your expertise. This gives me a good starting place.