Unfinished
Tales contains alot of late writing from
Tolkien about the Second and Third Age, plus two great stories from the First.
I & II - The Book of Lost Tales pt. 1 & 2 in the earliest writings that eventualy became The Simarillion.
III - The Lays of
Beleriand contains Tolkiens unfinished poems for the story of
Turin and
Beren and
Luthien. A truely amazing read.
IV - The Shaping of
Middle-earth contains the only full version of
The Silmarillion plus the first
map.
V- The Lost Road and other writings. The Lost Road is a story Tolkien never completed but gave rise to the tale of
Numenor. The book also contains all his writing on the Sil up until LOTR is started.
VI, VII, & VIII - The Return of the Shadow, The Treason of
Isengard, and The
War of the Ring all deal with the writing of LOTR.
IX -
Sauron Defeated. The first half finishes LOTR plus the original last chapter. The second half contains The Notion Club Papers and the later Fall of Numenor.
X & XI -
Morgoth's Ring and The War of the Jewels is all the later writings of the Sil from after LOTR till his death. My personal favorites.
XII - The
Peoples of Middle-earth deals with the appendix's of LOTR plus a few other later writings like the sequel to LOTR.