Get close to the nest above Firelink Shrine to talk to Snuggly the Crow. He will trade items for specific things that are dropped in her nest with the "Leave" item option in your inventory. Note: You can only do one trade per playthrough, however this resets with each New Game+. Warning: Do not exit the game with an item still resting on the ground before the trade has been completed or you will lose it.

Traded item	New item
Alluring Skull	Hello Carving
Avelyn	Titanite Scale
Black Firebomb	Titanite Chunk
Blacksmith Hammer	Titanite Scale
Caitha's Chime	Help Me! Carving
Cleric's Sacred Chime	Help Me! Carving
Coiled Sword Fragment	Titanite Slab
Crystal Chime	Help Me! Carving
Divine Blessing	Very good! Carving
Eleonora	Hollow Gem
Firebomb	Large Titanite Shard
Hidden Blessing	Thank you Carving
Homeward Bone	Iron Bracelets
Large Leather Shield	Twinkling Titanite
Lightning Urn	Iron Helm
Loretta's Bone	Ring of Sacrifice
Mendicant's Staff	Sunlight Shield
Moaning Shield	Blessed Gem
Priest's Chime	Help Me! Carving
Prism Stone	Twinkling Titanite
Rope Black Firebomb	Titanite Chunk
Rope Firebomb	Large Titanite Shard
Saint-Tree Bellvine	Help Me! Carving
Seed of a Giant Tree	Iron Leggings
Shriving Stone	I'm sorry Carving
Siegbräu	Armor of the Sun
Undead Bone Shard	Porcine Shield
Vertebra Shackle	Lucatiel's Mask
Xanthous Crown	Lightning Gem
Yorshka's Chime	Help Me! Carving