Because there's no sweeter potato than a POSSUM.

Undead possum named Pebble | Earthbound speedrunner | aro/ace | ADHD | bird hell shitposter refugee | probably older than you | antifascist and anticapitalist | U.S. | 🚮 | icon by my beloved @UrvogelArts
Because there's no sweeter potato than a POSSUM.
I regret to inform you that it's almost certainly because possum and sweet potatoes were a commonly paired dish in the American South for a rather long time period.