Although pretty and often used to control erosion, crown vetch is invasive in many parts of the US. Some recommended native alternatives: Round headed bushclover (Lespedeza capitata), purple prairie clover (Dalea purpurea), goat’s rue (Tephrosia virginiana), and partridge pea (Chamaechrista fasciculata). 
Scientific name: Securigera varia, syn. Coronilla varia
Common names: Crown vetch
Native Range: Africa, Europe, Asia
 “Crown Vetch” [https://mdc.mo.gov/sites/default/files/resources/2012/05/crownvetch.pdf, accessed May 31, 2017], Missouri Department of Conservation, 2012.