You cannot pick up a mound of sand.
2665h, 2240m, 2500e, 10p ex-probe sand

The sand that makes up this mound is very fine and sifts naturally as something
moves beneath it. A small dent in the top of the mound belies a hollow space
beneath the mound.
It weighs about 2 pounds and 0 ounce(s).
2665h, 2240m, 2500e, 10p ex-
With a clicking scurry, a black scorpion suddenly appears from the north.
2665h, 2240m, 2500e, 10p ex-spiritbond groundhog

You call upon the spirit of groundhog to grant you the gift of burrowing. Your
nostrils fill with the scent of earth and a taloned claw brushes your cheek
gently.
2665h, 2190m, 2500e, 10p x-
You have recovered equilibrium.
2665h, 2190m, 2500e, 10p ex-
Its barbed tail poised ready, a black scorpion scurries to the north.
2665h, 2190m, 2500e, 10p ex-burrow below

You are surrounded by utter darkness, and can see nothing. The smell of
minerals and dirt fills your nostrils.
You see some loose soil to the north, southwest, and northwest.
2665h, 2190m, 2500e, 10p e-
You have recovered balance on all limbs.
forge
2665h, 2190m, 2500e, 10p ex-
You are packed much too tightly into the earth to do that.
2665h, 2190m, 2500e, 10p ex-burrow above

Precarious ledge between the cliff and a crater.
The bright sun shines down, blanketing you with its life-giving warmth. A pile
of golden sovereigns twinkles and gleams. The dead body of a black scorpion
lies in a puddle of ichor. A hideous bobcat stands here, twitching and growling
sporatically. A mound of fine sand lies on the ground here.
You see exits leading north, southwest, and northwest.
A pair of muscular arms bursts forth from the mound of sand and, grabbing hold
of your ankles, pulls you down into a pit.
Burrowed underground.
There are 5 ruby vials here. There are 5 coral vials here. A garnet vial
glitters on the ground. There are 15 faeleaf stalks in 6 groups here. A plug of
coltsfoot lies on the ground here. There are 5 gyfu runes here. There are 9 cen
runes here. There are 14 blank rune stones here. A yarrow sprig has been tossed
on the ground. A kafe bean lies on the ground here. There are 2 emeralds in 2
groups here. A stone of jade glitters on the ground. There are 2 onyx gems in 2
groups here. An eoh rune has been carelessly dropped on the ground. An ur rune
has been carelessly dropped on the ground. A ger rune has been carelessly
dropped on the ground. An ing rune has been carelessly dropped on the ground.
An ansuz rune has been carelessly dropped on the ground. An eh rune has been
carelessly dropped on the ground. A tiwaz rune has been carelessly dropped on
the ground. A peorth rune has been carelessly dropped on the ground. There are
2 sparkleberries in 2 groups here. A bunch of pennyroyal lies on the ground. A
sprig of marjoram has been thrown to the ground. A piece of kombu seaweed lies
here. A reishi mushroom has been left here. There are 3 glowing powerstones
here. A rad rune has been carelessly dropped on the ground. There are 6 coal
pieces in 2 groups here. There are 81 iron bars in 4 groups here. An elegant
white letter is in danger of being soiled here. The Hand of Tzaraziko lies on
the ground here, gleaming with an inner light. There are 7 handful of golden
sands here. A clump of silvery mud has been unearthed here.
There are no obvious exits.
2665h, 2190m, 2500e, 10p e-
You have recovered balance on all limbs.
forge
2665h, 2190m, 2500e, 10p ex-
You are packed much too tightly into the earth to do that.
2665h, 2190m, 2500e, 10p ex-ih

You are packed much too tightly into the earth to do that.
2665h, 2190m, 2500e, 10p ex-ql

You are packed much too tightly into the earth to do that.
2665h, 2190m, 2500e, 10p ex-look

You are surrounded by utter darkness, and can see nothing. The smell of
minerals and dirt fills your nostrils.
You see some loose soil to the north, southwest, and northwest.
2665h, 2190m, 2500e, 10p ex-burrow above

Precarious ledge between the cliff and a crater.
A smattering of clouds fills the sky, lacing it with spiderwebs of grey. A pile
of golden sovereigns twinkles and gleams. The dead body of a black scorpion
lies in a puddle of ichor. A mound of fine sand lies on the ground here. A wild
yellow dog paws at the ground here, snarling and growling.
You see exits leading north, southwest, and northwest.
A pair of muscular arms bursts forth from the mound of sand and, grabbing hold
of your ankles, pulls you down into a pit.
Burrowed underground.
There are 5 ruby vials here. There are 5 coral vials here. A garnet vial
glitters on the ground. There are 15 faeleaf stalks in 6 groups here. A plug of
coltsfoot lies on the ground here. There are 5 gyfu runes here. There are 9 cen
runes here. There are 14 blank rune stones here. A yarrow sprig has been tossed
on the ground. A kafe bean lies on the ground here. There are 2 emeralds in 2
groups here. A stone of jade glitters on the ground. There are 2 onyx gems in 2
groups here. An eoh rune has been carelessly dropped on the ground. An ur rune
has been carelessly dropped on the ground. A ger rune has been carelessly
dropped on the ground. An ing rune has been carelessly dropped on the ground.
An ansuz rune has been carelessly dropped on the ground. An eh rune has been
carelessly dropped on the ground. A tiwaz rune has been carelessly dropped on
the ground. A peorth rune has been carelessly dropped on the ground. There are
2 sparkleberries in 2 groups here. A bunch of pennyroyal lies on the ground. A
sprig of marjoram has been thrown to the ground. A piece of kombu seaweed lies
here. A reishi mushroom has been left here. There are 3 glowing powerstones
here. A rad rune has been carelessly dropped on the ground. There are 6 coal
pieces in 2 groups here. There are 81 iron bars in 4 groups here. An elegant
white letter is in danger of being soiled here. The Hand of Tzaraziko lies on
the ground here, gleaming with an inner light. There are 7 handful of golden
sands here. A clump of silvery mud has been unearthed here.
There are no obvious exits.

Well, that's just plain odd.

I saw a similar thing on a log from Achaea though. I think there's a special room (a wizard did it!) that contains basically every item you dig up as part of a quest, and also everything that people bury underground. Someone somehow managed to burrow in there once, and it was filled with herbs, gold, comms, plus a few quest items (like the iron rod from Auntie Maim's quest). This looks like that room - I know you have to dig up the mud for a quest in Newton, you also have to dig up the Hand of Tzaraziko, and the golden sand for a Celestian quest.

I guess somehow a gravedigger managed to yank you down, but you happened to also be burrowed, so instead of causing Lusty to crash you just ended up in a weird room full of untouchable treasure. Count yourself lucky!

edit: You should probably also bug it, because it is a bug, just one that ended up with interesting results as opposed to deadly or plain annoying ones.

Yeah, we know about that bug. It's irritating.