https://www.mercurynews.com/2016/11/02/how-to-grow-a-compost-garden/
The queen of compost herbs is comfrey (Symphytum officinale), which produces many very large, hairy leaves. Its roots travel deep into the soil, and mine the subsoil for key nutrients like potassium, phosphorus, and calcium. Comfrey grows rather quickly which means leaves can be harvested several times per growing season.
We still have a nice clump of comfrey planted down at the edge of the barn. We had it for the goats, now we just trim it for the compost. It does grow fast.