Purple Deadnettle function and use

We have tons of those, I thought they were Comfrey so I let them grow tall.
Since they are not, now I wonder what they do to the soil and reading they are edible, wonder how I can use them.

They are a great winter ground cover. The mature and die in early spring before they compete with most garden plants. They add organic matter.

They are a good source of early nectar for bees.

Chickens like to eat them. I haven't tried them.

Here as an article mentioning deadnettle near the end. http://www.eattheweeds.com/henbit-top-of-the-pecking-order/

We use the top 3 inches of both plants, mixed with other greens. If you are going to use a longer length of deadnettle stems, it begins to taste musty. This can be countered with something spicey... mustard, or peppers, whatever. We use it in soups, salads, or as wilted greens sautéed with onions.