Eat the weeds.

There used to be a book of that title; I suspect it's out of print, if ebay/Amazon prices are any guide.  
From about £15 up to almost £130.
I know many "weeds" are edible; I've had a few omelettes this year with Wild garlic, dandelions and nettles in them.  I've also discovered there are lots of edible wild plants, some of which I knew already.
This one?  
I suspect may date back to a forgotten era. I know Alice included Watercress in salads and we had it in the "Waterfall" annually until winter every year.  This I.D.ed as "American land cress" under a diversity of names; found before it rained, while I was leek weeding.  It's every bit as peppery as its wet relative.