Tolkien Tide: Thingol & Melian and On the Eldamar
Of Thingol and Melian
A very short chapter describing how Thingol left the exodus and fell in love with a Maiar wandering the wilderness. These two create one of the elven fastnesses that survive Melkor's second reign. Their daughter will be Luthien.
The notable part is that Thingol meets Melian exactly as Beren will meet Luthien. He is struck speechless by her beauty and song, as well as the singing birds all around. Given Thingol's anger at Beren, it's important to note he is angry for Beren doing exactly as he himself did.
Of Eldamar and the Princes of the Eldalië
This describes how the elves settled into their major groups, apart from those that forsook the exodus previously.
The Valmar are so in love with the light of the trees they basically live on Manwë's mountain and kind of disappear from the tale.
The Noldor miss the stars and so end up closer to the edge of Valinor, foreshadowing their eventual passage back into it.
The Teleri end up on an island and then the furthest eastern shore of Valinor. This will, as they say, be important later.
We also get family trees of the major players in the eventual kinslaying and dark vows of revenge that create the plot of the rest of the First Age. It's funny that Galadriel is just offhandedly mentioned here.