Moonflowers are among the most fascinating plants to grow from seed. Although they tend not to say this on the seed packets, they sprout faster if you nick the seeds and then soak them in water for a few hours before expecting them to germinate.
I use a nail clipper to cut a small chunk out of the side of each seed and then after soaking I sprout them in the SproutMan's hemp bag. Of course, any sprouter would work.
These seedlings are just a couple days old and the photo on the left was taken eleven hours before the photo on the right, illustrating how fast these grow. Less than 24 hours ago, they were wrinkly yellow balls that had not yet burst through the tough skin around the seeds.
There may be faster growing plants in the universe, but I have yet to encounter one. Even Kudzu does not start out this fast.