Hey did you remember the deadline for the overworld contest? I didn't.
This is a set of overworld graphics that I tried my best to make look real nice. They have a bunch of ordinary Mario features so they should probably meet at least some of your overworld needs.
Also: they're square. Amazing.
Moderator's note: it's already mentioned in the readme, but to clarify it further: the included ExGFX change the 8x8 tiles used by the vanilla Layer 1 tiles. If you only insert and load the ExGFX and palette files, your Overworld will be filled with garbage tiles due to the new graphics affecting the default Layer 1 tile, which in vanilla was completely transparent. To address this, you have to, in Layer 2 8x8 Editor Mode, copy the new 8x8 Layer 1 tiles (found below the submaps) from the sample BPS's Overworld to the same location within your Overworld, so your Layer 1 tiles will use those instead.