The guard at Queen's Castle, above The Bog, lowers the gate only when you bring 7 Golden Feathers. None are ordinary pickups. Each one is tied to a named event. If you're stuck at 5/7 or 6/7, finish the event you haven't completed instead of searching rooms.
Events confirmed by two sources
- Shrine of the Seven Sons, Midnight Drench: go left from the boss room.
- Webdrench Inn escape: you get it when you escape the Innkeeper.
- Forest King, Autumn Forest: it's in the room with Ilda.
- Rebuild Looter: return all four Looter Parts.
- The party: give a passenger a ride to Club Casket on the far west side of the catacombs. One guide calls this Squinton's birthday party.
Events from one source
Based on one source.
Another guide says you get a feather for delivering a snail after the Gravedigger fight in the Burial Vault. That would make eight events, so one of the lists is wrong.
Sources: Whisper of the House walkthrough, Whisper of the House guide, MeowDB reference, Gamer Social Club 100% walkthrough.