As you know the A-Gear is able to land anywhere on ground or water but
you can't with other gears. There is a little bug in Edmont Valley that
makes you fall from the supply shop. This is how you do it: go in Edmont
Valley, land on the exact edge of the supply shop (opposite from the warp
gate to the desert), then move a little in your front and then turn around.
You will fall on the ground. You can even supply from the ground if you 
left your supply window opened but you can't go while on the ground in 
the exterior of the shop.