(due to not having the rights to Unfinished Tales, the Histories, the Silmarillion, or The Nature of Middle-Earth)

the story of Erendis and Aldarion

the demographics, population distribution, full religious practices, and full geography of Númenor

the full extent of Númenorean colonization and religious persecution against the Faithful

the full story of Tar-Míriel and Ar-Pharazôn

the name “Zigûr” and the extent of Morgoth-worship in Númenor

the full political nuance and long history of the King’s Men as an ideology

any information on Sindarin population movement into Lórinand and the Greenwood

Oropher’s ancestry and relationship to Doriath

Galadriel’s family history, Sindarin marriage and assimilation, and political ambitions

any details on the War of the Elves and Sauron, possibly including the fact that it happened at all

information on Celebrimbor’s captivity and the fall of Ost-in-Edhil (beyond the fact that it happened)

the name “Annatar” and the name “Gwaith-i-Mírdain”

details on the Last Alliance (such as Oropher’s xenophobia and his troops’ suffering for it)

the names “Aegnor/Aikanáro” and “Angrod/Angaráto” for Galadriel’s other brothers, and possibly the name Finrod

the full extent of the Darkening and the political drama surrounding House Finwë

who Fëanor was and what he did

Fingon, Maedhros, and the other Finwëans of that generation (except maybe Turgon and Idril)

details of the War of Wrath

the names of most of the Valar, probably also the Khuzdul name “Mahal”

full details of the rounding of the world