This pretty volunteer showed up in my garden one day. I noticed sulphur butterflies seemed to like it too, and it turns out that it is a host plant for them. What I didn’t want to know is that it is considered by some to be one of the world’s worst weeds. In America, in particular, it is controlled with herbicides because it competes for resources with agricultural crops, and it carries Asian soybean rust disease as well. 
In Asia and Africa it is more highly regarded and is often used as food or medicine. In the Sudan, leaves are fermented and then dried and eaten as a source of protein. 
In India the leaves and seeds are considered laxative, anthelmintic, ophthalmic, cardiotonic and expectorant. The leaves and seeds are used for ringworm, flatulence, colic, dyspepsia, constipation, cough, bronchitis, and cardiac disorders, among other things. 
One study  determined that extracts of S. obtusifolia demonstrated a broad-spectrum of activity against both gram-positive and gram-negative bacteria and fungi, which the authors concluded may confirm its use in traditional medicine.
Caterpillars have nearly denuded the plant in my garden at least a couple of times, but there are several long seed pods still attached. They look a lot like haricot verts. I’ll save them and figure out what to do with them later. They’ve been roasted and used as a coffee substitute in some places …maybe that.
Scientific name: Senna obtusifolia, syn. Cassia obtusifolia
Common names: Sicklepod, arsenic weed, Java-bean, Jue-ming-zi
Nativity: Probably tropical America, but it has naturalized around the world
 Larry Steckel, “Sicklepod,” Extension.tennessee.edu/publications/Documents/W125.pdf, accessed November 7, 2016.
 Steven Foster and Yue Chongxi, Herbal Emissaries: Bringing Chinese Herbs to the West, Healing Arts Press, 1992, pp. 311–317.
 Pankaj Oudhia, “Charota or Chakad,” Hort.purdue.edu/newcrop/CropFactSheets/cassia.html, accessed November 6, 2016.
 Doughari, El-mahmood, A. M. and Tyoyina, I.”Antimicrobial activity of leaf extracts of Senna obtusifolia (L),” www.academicjournals.org/article/article1380814322_Doughari%20et%20al.pdf, accessed November 6, 2016.