This post is pretty much just what it says on the tin!
Using the excellent RODE recording app for iPhone (though not their iPhone mic) I got, precisely, the sound of the wind in the marsh grass when out walking in the evening recently. I held the iPhone right in amongst the grasses which had the added advantage of muffling the sound of traffic on the motorway as well as stopping the rumble effect of the wind directly on the mic.
These field recordings on their own are not going to be for everyone but I enjoyed listening to the changing sounds of the grasses as the wind strength changed and find, as with the recording I do for StillWalks videos, that the sound does so much to help visualize the memory.
Surprisingly I find the sound peaceful, even though it sounds furious
I agree. I like the sound – it is one of the attractions of the marshes for me.