Have any of you tried using a beneficial cover crop as a ground cover in a garden bed?

I sowed Daikon radish seeds in bare areas of my flowerbed, and the foliage is looking rather nice. Maybe I should thin them, but they look so nice. When they're mature, I'll mix the foliage in with the soil, leaving the roots to decompose and be good organic matter.

I assume I could do the same thing with clover to add nitrogen, as long as I killed it and mixed it in with the soil when it was about to bloom, so it wouldn't use the nitrogen it had accumulated for flowering and setting seed.

Has anyone grown dual-purpose plants as ground covers and cover crops? What do you think of the idea?

If you have clay soil, radishes are the best cover.
I have planted radishes and just let them go to seed, fairly often.
Some types have tasty seed pods and as you said, they are good for the soil.