Once Mom's Shovel is complete, the stomping caused by Broken Shovel stops.
Unlike the Broken Shovel, Mom's Shovel will not disappear if it is left on a pedestal, and Isaac leaves and re-enters the room it was left in.
Like We Need To Go Deeper!, this item can be used to destroy rocks if used while Isaac is flying over a rock.
This item can be obtained by using Spindown Dice on Mucormycosis without obtaining the Broken Shovels.
The full Mom's Shovel can be found within the area of Death Certificate. Even without unlocking the item, its effect can potentially be activated by Metronome.
Synergies
Book of Virtues: Creates two wisps on the middle ring: one looks like The Forgotten, which has increased HP but does not fire tears, and the other looks like The Soul, which fires tears that have a 10% chance of invoking II - The High Priestess on enemies.
This item could be a reference to Ending 20, where Isaac is found dead inside the chest being nothing but skeletal remains, and this item was what Mom used to bury Isaac underground.
This is seen in The Forgotten Update trailer, where Mom is burying Isaac's remains, along with The Gamekid, and possibly other items he had with him.
Broken Shovel and the 
Broken Shovel.
Crawl Space, identical to 
We Need To Go Deeper!.
Dark Room will unlock 
The Forgotten.
Chest.
The Negative has not yet been unlocked by teleporting straight to the dark room via a 
Sacrifice Room.
???, 
Sheol, 
Cathedral, 
Chest, 
The Void, or 
Home.
Spindown Dice on 
Mucormycosis without obtaining the Broken Shovels.
Death Certificate. Even without unlocking the item, its effect can potentially be activated by 
Metronome.
Book of Virtues: Creates two wisps on the middle ring: one looks like 
The Soul, which fires tears that have a 10% chance of invoking 
II - The High Priestess on enemies.
Mom used to bury Isaac underground.
The Gamekid, and possibly other items he had with him.
The Binding of Isaac: Rebirth
