Good times. I still remember reading the Darkwalker Trilogy back in the late 80s.
Moonshae Isles Regional Guide (Baldman Games, DM’s Guild)
Probably the single biggest 5e expansion for the isles. It fleshes out the Ffolk, Northlanders, factions, geography, and gives Moonshae-specific character options and backgrounds, plus ties into the AL adventures.
Five Temples of the Earthmother adventure series (DM’s Guild)
A multi-part campaign set on Alaron; each chapter centers on a different temple of the Earthmother and local threats. It’s written for the Moonshaes, so you can drop it straight into your campaign or cannibalize locations, NPCs, and rituals.
Secrets of Flamsterd’s Isle (high-level Moonshae adventure)
Epic-tier AL adventure on Flamsterd’s Isle in the isles, dealing with ancient Moonshae threats. Great if your group eventually pokes at legendary wizard ruins or Earthmother relics.
The Moonshae / Darkwalker trilogy novels
FR2 Moonshae Isles (AD&D)
Kobold Press offerings:
Courts of the Shadow Fey (Kobold Press, 5e)
150-ish page planar/fey court campaign (levels ~7–10) full of intrigue, duels, and dangerous social maneuvering in the Shadow Realm.
Wrath of the River King (Kobold Press, 5e)
A very “classic fairy tale gone wrong” adventure where a fey lord has claimed a mortal village. Widely praised as one of the most “properly fey” adventures out there.
Shadows of the Dusk Queen (Kobold Press)
Mid-level fey forest dungeon with a sinister fey queen and a twisted woodland. Great for plugging into a Moonshae forest or island sacred to the Earthmother.
Dark Fey (Kobold Press, 3pp supplement)
Short but potent book detailing several fey courts (River Court, Moonlit Court, Court of a Million Stars) plus 18 new malevolent fey and a fey animal template.
The Feywild Companion (DM’s Guild)
Big 5e toolkit for fey campaigns: new lineages, subclasses, spells, items, optional rules, random encounters, and a mid-length fey adventure, all themed around fey realms.