I ate a pennywort leaf today. It tasted like a rather musty leafy green leaf from a plant in a wall. I can see why it hasn't become a wild-food must-taste menu item. Or perhaps it has.
The frost seems a long time ago now.
(The photo above reminded me of a Roman tile from the museum of Verulamium at St Albans, near where I grew up. The tile had a two thousand year old dog paw print in it, and a stone which, one imagined, was thrown at the dog two thousand years ago to get it off the wet clay tiles. I haven't searched the website yet to see if it appears there...)