[Urwen]

I've figured it out!

When spring unfolds the beechen leaf upon a sunny day, - There was sun shining, and the branches of trees were waving and tossing in the wind
When endless the assent, and pointless seems the long foray, - Then he seemed to see himself going along a dim passage, and climbing
an endless winding stair.
When red the walls and bleak the view and black smoke fills the air - a large red-brick building was being put up where it had stood; Black smoke seemed to cloud the surface of the Mirror
You must turn back! You must return! You must not linger here! - ‘I can’t stay here,’ he said wildly. ‘I must go home. They’ve dug up Bagshot Row, and I must go home!’

When mountain peaks loom in the sky and day to twilight fades, - Mountains loomed dark in the distance against a pale sky
When friend unlooked for's seen again, and friend long-missed awaits, - Far away a figure came slowly down the road, faint and small at first, but growing larger and clearer as it approached; Brief and small but very vivid he caught a glimpse of Bilbo walking restlessly about his room.
When enemy is tracking you like hunter tracks his prey - Then the Eye began to rove, searching this way and that; and Frodo knew with certainty and horror that among the many things that it sought he himself was one.
You must remain and carry on, you have no other way.

When what is dear is tarnished by malevolence and guile, - The Scouring of the Shire
Old friends are fallen on the road, and homes in ruin lie, - he saw Frodo with a pale face lying fast asleep under a great dark cliff
When barrow holds what little treasures left the hill intact - there’s the poor old Gaffer going down the Hill with his bits of things on a barrow.
Don't linger here beneath the stars! Return! You must turn back! - 'I must go home!’

When battle breaks and prophecies of old will come to pass, - A smoke as of fire and battle arose, and again the sun went down in a burning red that faded into a grey mist
When you are taking up the tale from heroes of the past, - Huey explained this one
When tempests rage and vessels sail to build, save, and depart - and into the mist a small ship passed away, twinkling with lights
You must stay here and carry on, you must fulfill your part. - Being a mayor etc

You know that you must walk this road together with a friend, - ‘No, I’ll go home by the long road with Mr. Frodo, or not at all,’ he said. ‘But I hope I do get back some day. If what I’ve seen turns out true, somebody’s going to catch it hot!’
But what saw you before all this, which he saw at the end? - ‘There’s only stars, as I thought,’ he [Sam] said; and Frodo found that he was looking at the cool stars twinkling in
the silver basin


(Is that it?)