This item has a 12.6% chance to spawn from paying out a Beggar in addition to being in the Beggar item pool. Multiple copies can be obtained through this method.
If the Treasure Room Pool runs out of items, it will only contain Breakfast from that point onwards.
Once other item pools run out of items, they will only contain Treasure Room Pool items. This means that if the Treasure Room Pool was also exhausted, that item pool will only contain Breakfast.
With Chaos, every fully depleted item pool will only contain Breakfast.
Breakfast spawned via exhausted item pools cannot be rerolled into other items with a few exceptions:
Rerolling Breakfast from an exhausted item pool while holding Chaos can reroll it into an item from another pool.
Dropping NO! after exhausting an item pool while holding it will allow active items to spawn on pedestals again.
Having an item spawn from a non-exhausted pool before picking up Breakfast can allow rerolls to collected passive items (e.g. D4) to reroll Breakfast into an item from that item pool.
Losing Sacred Orb after exhausting an item pool while holding it will allow low quality items to appear again.
Synergies
Binge Eater: When Isaac picks up Breakfast it now grants: a permanent +0.2 Shot Speed and +2.5 Range, a temporary +3.6 Damage (which diminishes to 0 in 30 seconds), heals 1 additional red heart, and takes a permanent -0.03 Speed reduction.
Heals 1 additional 
Red Heart.
Beggar in addition to being in the Beggar item pool. Multiple copies can be obtained through this method.
With 
Chaos, every fully depleted item pool will only contain Breakfast.
Soul of Eden.
NO! after exhausting an item pool while holding it will allow active items to spawn on pedestals again.
Having an item spawn from a non-exhausted pool before picking up Breakfast can allow rerolls to collected passive items (e.g. 
D4) to reroll Breakfast into an item from that item pool.
Sacred Orb after exhausting an item pool while holding it will allow low quality items to appear again.
Binge Eater: When Isaac picks up Breakfast it now grants: a permanent +0.2 Shot Speed and +2.5 Range, a temporary +3.6 Damage (which diminishes to 0 in 30 seconds), heals 1 additional red heart, and takes a permanent -0.03 Speed reduction.
