Snuggly the Crow

Hawk Girl is an invisible NPC in Dark Souls. She's just like Double-Winged Hawk Girl in Demon's Souls, in the way that you can trade particular items with her to recieve other useful items.

Exchanges
This lists all currently known exchanges with the Hawk Girl in alphabetical order:

Bloodred Moss Clump ---> Twinkling Titanite Blooming Purple Moss Clump ---> Twinkling Titanite x2 Cracked Red Eye Orb ---> Purging Stone x2 Dried Finger ---> Blue Titanite Chunk Dung Pie ---> Demon Titanite Egg Vermifuge ---> Dragon Scale Humanity ---> Ring of Sacrifice Pendant ---> Souvenir or Reprisal Prism Stone ---> Demon Titanite Pyromancy Flame ---> Red Titanite Chunk Pyromancy Flame ---> Red Titanite Slab Purple Moss Clump ---> Twinkling Titanite Rubbish ---> Titanite Chunk Ring of the Sun Princess ---> Divine Blessing x2 Sack ---> Demon's Great Hammer Skull Lantern ---> Ring of Fog Sunlight Maggot ---> Old Witch's Ring Sunlight Medal ---> White Titanite Chunk Twin Humanities ---> Rare Ring of Sacrifice Xanthous Crown ---> Ring of Favor and Protection