Mellyrn don't sing, do they?

[Mithalwen]

Valley of the singing gold is a little poetic but if you think that Lorian elves actually lived in the trees and all elves love to sing it isn't that fanciful.

The use of singing and music as a expression of (for want of a better term though I think it unsatisfactory) magical power has been exprlored elsewhere but I would just say that Arwen the actual and symbolic heir of Luthien, the most notable proponent of this skill, sings while the sapling of the White Tree makes its unnaturally speedy growth and the mallorn seed, gift of the lady who sang of leaves of gold makes similarly freaky progress when Sam plants it in the Party Field.

Mallorns my be a more generic memory of Laurelin than the more specific likeness that the White trees of Numenor and Gondor are of Telperion but I think it is clear that they are the heirs in fact if not intention. It is possible that Tolkien wrote it without noticing the significance, and the mallorn was no more than a gift to a gardener and lover of trees, but if so it is the most beautiful and fitting coincidence that the final destruction of Melkor's servant, Sauron, is marked by the flourishing of two trees of silver and gold.