Dirt Tunneler
Neuromancer

Makes dirt deeper and you can tunnel through it just by walking through it. Press spacebar/shift to tunnel upward/downward with auto placed ladders.

Mud
Blocky Player

Adds stylish mud blocks and even blocks you can walk through. Setup traps, secret rooms and much more!

Silver
Jackknife

adds silver ore and tools

Too many ores
TeufloV

This adds 53 new ores. But most of them are useless.