That looks like a pole bean with the vines looking for more ways to go up. That support there will get quickly over run if that is the case. My pole beans went up over 6 ft and started growing all over each other in a messy mass.
Some bean plants have different colored flowers, so starting out white and getting yellowish before the flowers fall and the beans start to grow is a bit of a help. It narrows it down, but not by much. Like the others have said, the best we can say is that it is some kind of bean. My blue lake pole beans look exactly like that, but many many others do too.
