Using the roots, Soapwort, will produce a lather in the bowl, so it is possible to grow your own soap! Keep it in check thought as it can quickly spread like a weed.
Saponaria officinalis is a common perennial plant from the carnation family. This plant has many common names, including common soapwort, bouncing-bet, crow soap, wild sweet William, and soapweed. There are about 20 species of soapworts altogether.