This is a curious one. Anyone who has played old-school D&D has at least heard of this spell. In my experience, it doesn't get used much unless magic-using characters roll their starting spell randomly. When your entire magical arsenal for the day consists of one or two first level spells, a luggage cart just isn't likely to be your first choice.
Floating Disc (from Moldvay)
Duration: 6 turns
Without quoting the whole spell description, the disc of magical force appears at the caster's waist height and stays no more than 6' away from him or her as they move about. It can carry 5000 coins in weight (500 lb.) and moves at the caster's movement rate.
Because it's a utility spell with next to no combat application (not to discourage player creativity), it has a decent duration. It's not all day, but an hour from a first level spell isn't bad. Since it basically dumps what it's carrying on the ground when the spell ends, you probably aren't going to use it as a caddie.
Here's where the spell gets interesting.
Five thousand coins carrying capacity. That's more than a mule can carry! The disc floats along behind he caster at the same movement speed. That means your unarmored, unencumbered, 120' per turn magic-user can carry more than a pack animal out of the dungeon faster than the big, brawny fighter. So one tactic for recovering as much loot as possible might be to load up the wizard's disc and have him sprint for the surface, towing the treasure. He can also carry out a wounded/fallen comrade.
Nothing in the spell indicates the caster needs to maintain the spell, so he's free to cast others if he has them, fight, talk, map, etc. It's described as the size and shape of a small round shield, which I interpret as about 2-3' in diameter. I find that an odd size for carrying the much weight.
I'm not saying I would want to play a 1st level MU going into the Caves of Chaos with FD as my only spell, but I wouldn't say no to a scroll for the spell.