So here is the complete list of items which can be dug according to the biome it is placed on. It is a direct copy paste of the table which is used by the scripts so it looks a bit strange, but you should be able to understand.

MMLOOTTABLE = {}

MMLOOTTABLE["BIOME_"..GROUND.ROCKY] =
{
TIERONE =
{
tierthreshold = 0.7,
rocks = 0.33,
flint = 0.67,
nitre = 1,
},

TIERTWO =
{
tierthreshold = 0.91,
mnzironore = 0.38,
goldnugget = 0.67,
redgem = 0.84,
bluegem = 1,
},

TIERTHREE =
{
tierthreshold = 1,
marble = 0.67,
moonrocknugget = 1,
},

CHESTMOBS =
{
bat = 0.33,
slurtle = 0.67,
snurtle = 1,
},

ESCAPEMOBS =
{
rocky = 1,
}
}

MMLOOTTABLE["BIOME_"..GROUND.DIRT] =
{
TIERONE =
{
tierthreshold = 0.38,
rocks = 0.61,
flint = 1,
},

TIERTWO =
{
tierthreshold = 0.87,
boneshards = 0.41,
mnzironore = 0.61,
goldnugget = 0.75,
redgem = 0.85,
houndstooth = 1,
},

TIERTHREE =
{
tierthreshold = 1,
trinket_8 = 0.15,
trinket_7 = 0.30,
sunken_boat_trinket_2 = 0.45,
sunken_boat_trinket_5 = 0.60,
lightninggoathorn = 0.83,
dragon_scales = 1,
},

CHESTMOBS =
{
slurper = 0.33,
bat = 1,
},

ESCAPEMOBS =
{
rocky = 0.5,
spider_spitter = 0.5,
}
}

MMLOOTTABLE["BIOME_"..GROUND.SAVANNA] =
{
TIERONE =
{
tierthreshold = 0.6,
rocks = 0.23,
flint = 0.56,
nitre = 1,
},

TIERTWO =
{
tierthreshold = 0.81,
goldnugget = 0.33,
mnzironore = 0.81,
horn = 1,
},

TIERTHREE =
{
tierthreshold = 1,
manrabbit_tail = 0.26,
slurper_pelt = 0.42,
orangegem = 0.58,
trinket_2 = 0.69,
trinket_3 = 0.80,
trinket_11 = 0.91,
trinket_9 = 1,
},

CHESTMOBS =
{
bat = 0.5,
monkey = 1,
},

ESCAPEMOBS =
{
bunnyman = 1,
}
}

MMLOOTTABLE["BIOME_"..GROUND.GRASS] =
{
TIERONE =
{
tierthreshold = 0.7,
rocks = 0.33,
flint = 0.76,
nitre = 1,
},

TIERTWO =
{
tierthreshold = 0.89,
mnzironore = 0.32,
goldnugget = 0.58,
boneshard = 1,
},

TIERTHREE =
{
tierthreshold = 1,
trinket_1 = 0.18,
trinket_4 = 0.36,
trinket_5 = 0.54,
trinket_13 = 0.73,
yellowgem = 1,
},

CHESTMOBS =
{
bat = 0.5,
mole = 1,
},

ESCAPEMOBS =
{
bunnyman = 0.66,
rocky = 1,
}
}

MMLOOTTABLE["BIOME_"..GROUND.FOREST] =
{
TIERONE =
{
tierthreshold = 0.6,
rocks = 0.25,
flint = 0.58,
nitre = 1,
},

TIERTWO =
{
tierthreshold = 0.9,
lightbulb = 0.17,
goldnugget = 0.50,
mnzironore = 0.83,
bluegem = 1,
},

TIERTHREE =
{
tierthreshold = 1,
mandrake = 0.5,
greengem = 0.8,
slurtlehat = 1,
},

CHESTMOBS =
{
bat = 0.33,
spider_dropper = 0.67,
monkey = 1,
},

ESCAPEMOBS =
{
bunnyman = 0.4,
spider_hider = 0.73,
spider_spitter = 1,
}
}

MMLOOTTABLE["BIOME_"..GROUND.MARSH] =
{
TIERONE =
{
tierthreshold = 0.7,
wetgoop = 1,
},

TIERTWO =
{
tierthreshold = 0.85,
purplegem = 0.33,
cutlichen = 0.33,
tentaclespots = 1,
},

TIERTHREE =
{
tierthreshold = 1,
trinket_12 = 0.33,
trinket_6 = 0.33,
tentaclespike = 1,
},

CHESTMOBS =
{
monkey = 0.33,
spider_dropper = 0.67,
snurtle = 1,
},

ESCAPEMOBS =
{
spider_hider = 0.33,
spider_spitter = 0.67,
spider_dropper = 1,
}
}

MMLOOTTABLE["BIOME_"..GROUND.CARPET] =
{
TIERONE =
{
tierthreshold = 0.4,
},

TIERTWO =
{
tierthreshold = 0.94,
marble = 0.56,
gears = 0.75,
purplegem = 0.94,
redgem = 0.97,
bluegem = 1,
},

TIERTHREE =
{
tierthreshold = 1,
greengem = 0.33,
yellowgem = 0.67,
orangegem = 1,
},

CHESTMOBS =
{
slurper = 0.75,
bat = 1,
},

ESCAPEMOBS =
{
knight_nightmare = 0.5,
bishop_nightmare = 1,
}
}

MMLOOTTABLE["BIOME_"..GROUND.DECIDUOUS] =
{
TIERONE =
{
tierthreshold = 0.6,
rocks = 0.25,
flint = 0.50,
nitre = 0.75,
feather_crow = 0.83,
feather_robin = 0.91,
feather_robin_winter = 1,
},

TIERTWO =
{
tierthreshold = 0.85,
mnzironore = 0.4,
goldnugget = 0.8,
coontail = 1,
},

TIERTHREE =
{
tierthreshold = 1,
transistor = 0.33,
glommerfuel = 0.67,
greengem = 1,
},

CHESTMOBS =
{
bat = 0.4,
monkey = 0.7,
mole = 1,
},

ESCAPEMOBS =
{
bunnyman = 0.5,
spider_hider = 0.5,
}
}

MMLOOTTABLE["BIOME_"..GROUND.DESERT_DIRT] =
{
TIERONE =
{
tierthreshold = 0.38,
rocks = 0.61,
flint = 1,
},

TIERTWO =
{
tierthreshold = 0.87,
boneshards = 0.41,
mnzironore = 0.61,
goldnugget = 0.75,
redgem = 0.85,
houndstooth = 1,
},

TIERTHREE =
{
tierthreshold = 1,
trinket_8 = 0.15,
trinket_7 = 0.30,
sunken_boat_trinket_2 = 0.45,
sunken_boat_trinket_5 = 0.60,
lightninggoathorn = 0.83,
dragon_scales = 1,
},

CHESTMOBS =
{
slurper = 0.33,
bat = 1,
},

ESCAPEMOBS =
{
rocky = 0.5,
spider_spitter = 0.5,
}
}