Experts and BHG readers answer.
How do I find a certain type of climbing vine?
It's difficult to tell from your description exactly what the plant might be. However, I suspect that the vine in question might be hyacinth bean (Dolichos lablab, or Lablab purpureus). The seeds of this plant are a 2-toned bean, almost black with white along one side. The flowers come in long racemes on the vining plant. Seeds of it are available from a number of mail order suppliers such as Park Seed or Renee's Garden.