18 cards where the illustration contains “feathered-cap”

Bombadil's Song (The Lord of the Rings: Tales of Middle-earth #154)
Breeches, Brazen Plunderer (Commander Legends #165)
Breeches, Eager Pillager (The Lost Caverns of Ixalan #294)
Capashen Knight (Urza's Destiny #3)
Coastline Marauders (Commander Legends #168)
Discerning Financier (Wilds of Eldraine #10)
Errand of Duty (Masters Edition II #12)
Merchant Raiders (Commander Legends #81)
Narrow-Minded Baloney Fireworks (Unfinity Sticker Sheets #12)
Pirate Hat (The Lost Caverns of Ixalan #70)
Ramirez DePietro, Pillager (Dominaria United Commander #38)
Seller of Songbirds (Return to Ravnica #22)
Shapeshifter (Lorwyn Tokens #11)
Timestream Navigator (Rivals of Ixalan #59)
Tom Bombadil (The Lord of the Rings: Tales of Middle-earth #745)
Unlucky Drop (The Lost Caverns of Ixalan #82)
Walking Desecration (Onslaught #180)
Wanderlust (Limited Edition Alpha #226)

Though this query has ended, its relics still slumber in New Argive.