Something else I've done with mustard leaves, which re-seeded themselves from a first planting with vigor: use them as green mulch. I pulled a bunch and put them under a rose that was pretty sad and it burst into green growth after a year of just sitting there.

I always planted wild mustard in SC, but I had to stop eating it, because the oxalic acid in it was causing me problems with my bad kidney. I can eat a tiny bit of mustard mixed with other greens. I like mixing it with collards to give it a little zing.

You got me worried so I looked it up. Apparently oxalic acid is not an issue for healthy people but can be an issue in some cases

"What Is Oxalic Acid?

Oxalic acid is a naturally occurring chemical in plants and animals and is also consumed in a variety of different foods such as leafy greens, nuts, seeds, most berries, certain fruits, soy and soy products, meat and dairy products. In large amounts, oxalic acid is poisonous, but toxic levels are not found in foods that we normally eat.

The main controversy surrounding oxalic acid in food is whether or not they contribute to the formation of kidney stones. About 80% of the kidney stones formed by adults in the U.S.A. are composed of calcium oxalate. Oxalic acid binds with other minerals such as calcium which form a salt known as an oxalate. Oxalic acid interferes with the absorption of calcium in foods because they bind with it, making it unusable by your body. Without oxalic acid, foods such as spinach and kale would have a much higher, bio-available calcium content than they do because it is bound up with oxalic acid. These oxalates are usually passed though the urine but in vulnerable individuals, they may crystallize, forming larger stones that cause excruciating pain and require medical attention."

And some detailed information on oxalates from WHole Foods

Here is a link that might be useful: Oxalates

This is also what I found in my research"

"The cholesterol-lowering ability of steamed mustard greens is second only to steamed collard greens and steamed kale in a recent study of cruciferous vegetables"

"rank high on the list of commonly eaten cruciferous vegetables, and in one study, were second only to Brussels sprouts in terms of total glucosinolate content. Glucosinolates are phytonutrients that provide us with unique health benefits because they can be converted into isothiocyanates (ITCs) that have cancer-preventive properties. "

And many others benefits and a high source of calcium.

More details on link below.

Here is a link that might be useful: On mustard health

Yes, they are o.k. for anyone who doesn't have kidney problems, but believe me, if you do (I have a spongey kidney on one side), the pain isn't worth the benefits. I have to be very careful of how much of oxalate containing veggies I eat, which is sad, because they are some of my favorites. There ar so many plants that have oxylates, like some of the tropical root veggies and cranberry hibiscus.