As further proof of my contention that anyone that talks to me about herbs will invariably teach me something cool…
I had a 12 year old kid come to my practice to follow me around a little. He wants to be a vet when he grows up so I invited him to spend the day at the clinic. We also took a putter through some of the herb beds. While I was showing him some of the plants, he pointed to a weed in the driveway and asked what it was. I told him I didn’t know.
He said: “I don’t know either but you can eat the flowers. They taste like radishes.“
I grabbed one and, sure enough, it tasted like a radish. I got my copy of Weeds of the West* and found the rascal.
Blue Mustard Chorispora tenella

Turns out both leaf and flower are edible and quite tasty (at least when they’re young). Apparently not medicinal, but definitely worth knowing about as a wild edible. I have a whole field full of it.
Doc
* Weeds of the West: 
Don't use herbs or combine herbs with medications or use them during lactation or pregnancy without talking with your healthcare provider.