"Milky Way" is apparently a form of Ipomoea purpurea, which may have black seeds (checked photos on Internet). The one that most often showed off-white seeds was Ipomoea alba, which is the Tropical White Morning glory. That one is sometimes called (incorrectly, it seems) "Moonflower".

This info is just from Google searches. I am not knowledgeable about commercially produced plants.

Thanks jekeesl, I think they are supposed to be black, too. Just wanted to be sure before I traded them.