Yeah, mules carrying mattresses is like "dog bites man." I was hoping for something more "man bites dog," like some mules taking a nap on a mattress.
On a related note, I recall seeing a story once about how mules are used to carry the mail and deliver goods down to some village in the Grand Canyon (Havasupai tribe, maybe?). And I'm about 99% sure they showed a picture of a mule carrying a small refrigerator down the trail.
Mules can pack everything from pianos (modest sized) to cookstoves (ditto). Thousands of feet of wire cable can be transported by hanging an equal number of coils on either side of the mule, then proceeding to the next mule, until you run out of wire cable. Continuous loads like that fascinate me because there are so many things that can go wrong, taking that cable up mountain trails to the tram sites. They can also haul full-sized telephone poles with multiple mules, using pack saddles with swivels that accommodate the different angles as the mules take the trail.
"I couldn't fix your brakes, so I made your horn louder."