Considering how prolific seeders all the morning glory family is, if you're talking about Ipomoea Alba type of moonflower, I promise you'll have them back next year if you let them volunteer seed themselves. They will/should die back complete from the first frost though, so they're in that "kinda perennial" grouping.

Thanks for the tip on the Moon flower. I'll save seed just in case, then sow again. I was really surprised they came up within a week considering the size and hardness of the seed and I forgot to soak them.

lol, first time I saw them I thought I got a pack of garbanzo beans instead. hard to believe that the seed pods that form will have upwards of 10 of them each... ;-p

Here is a link that might be useful: