[Nerwen]

I believe Findegil's right. Note that Tasirinan (=Nan-tathren) was in Beleriand, not Valinor.

The song about the Ents and Entwives in The Lord of the Rings does perhaps hint at them going to Valinor ("together we will take the road that leads into the west"), however if so I think that's meant to be wishful thinking. I don't have the books with me right now, but from memory, doesn't Treebeard himself regard it as a bit of Elven whimsy, rather than a prophecy?

EDIT:X'd with Galin.