Bone

Dropped by

• Bogged
• Skeleton
• Skeleton Horse
• Stray
• Wither Skeleton
• Aptrgangr (L_Ender's Cataclysm)
• Daemonium Corrodis (Neo Vitae)
• Daemonium Rancoris (Neo Vitae)
• Draugr (L_Ender's Cataclysm)
• Dread Beast (Ice And Fire Community Edition)
• Dread Ghoul (Ice And Fire Community Edition)
• Dread Knight (Ice And Fire Community Edition)

And 21 more.

Dropped when you break

• Honey Glazed Ham
• Urn

Found in chests

• Ancient City
• Desert Pyramid
• Jungle Temple
• Simple Dungeon
• Woodland Mansion
• Abandoned Temple Entrance (When Dungeons Arise)
• Abandoned Temple Map (When Dungeons Arise)
• Abandoned Temple Top (When Dungeons Arise)
• Ancient Cities Nether (Repurposed Structures)
• Ancient Cities Ocean (Repurposed Structures)
• Bandit Towers Barrels (When Dungeons Arise)
• Bandit Towers Normal (When Dungeons Arise)

And 145 more.

Caught fishing

• Junk
• Open water
• Junk (Eternal Starlight)
• Open water (Eternal Starlight)

Brushed out of suspicious sand or gravel

• Ancient Shrine Suspicious (The Bumblezone)
• Battle Cubes Suspicious (The Bumblezone)
• End Sand (MoogsEndStructures)
• Fortress Jungle (Repurposed Structures)
• Monument Jungle (Repurposed Structures)
• Pollinated Stream Suspicious (The Bumblezone)
• Sempiternal Sanctum Blue Suspicious (The Bumblezone)
• Sempiternal Sanctum Green Suspicious (The Bumblezone)
• Sempiternal Sanctum Purple Suspicious (The Bumblezone)
• Sempiternal Sanctum Red Suspicious (The Bumblezone)
• Sempiternal Sanctum White Suspicious (The Bumblezone)
• Sempiternal Sanctum Yellow Suspicious (The Bumblezone)

And 1 more.