The Handkerchief is a trinket.
They have two colors per trinket, and thus 729 unique versions:
Navy/white handkerchiefs were readily available in the daily Cleaver's Blue Hanky automated swordfighting tournament. Purple/blue handkerchiefs are rewarded as a prize in the Drown Yer Sorrows Drinking tournament.
|Other Available Trinkets|
|Bone | Comb | Daisies | Daisy | Fancy ribbon | Handkerchief | Lilies | Lily | Long stem rose | Lump of coal | Mirror | Orchid | Orchids | Parrot feather | Ribbon | Rose | Roses | Signet ring | Skull | Tuft of fur | Zombie hand|