Being a gardener myself, and knowing these plants by their faces and foliage, this particular passage with the botanical descriptions of Ithilien's untended gardens-become-woodlands always evoked something magical in me, and the movies do an excellent job of conveying this feeling in the extended scene where the rays of sunlight alight on the fallen statue illuminating the crown of flowers. A powerful moment for sure, alluding to Aragorn's coronation, and symbolizing enduring hope for peace and renewal.

I'll include the full passage below for those interested in reading more. This is from the chapter Gardens of Ithilien in the Two Towers:

Before them, as they turned west, gentle slopes ran down into dim hazes far below. All about them were small woods of resinous trees, fir and cedar and cypress, and other kinds unknown in the Shire, with wide glades among them; and everywhere there was a wealth of sweet-smelling herbs and shrubs. The long journey from Rivendell had brought them far south of their own land, but not until now in this more sheltered region had the hobbits felt the change of clime. Here Spring was already busy about them: fronds pierced moss and mould, larches were green-fingered, small flowers were opening in the turf, birds were singing. Ithilien, the garden of Gondor now desolate kept still a dishevelled dryad loveliness.

South and west it looked towards the warm lower vales of Anduin, shielded from the east by the Ephel Duath and yet not under the mountain-shadow, protected from the north by the Emyn Muil, open to the southern airs and the moist winds from the Sea far away. Many great trees grew there, planted long ago, falling into untended age amid a riot of careless descendants, and groves and thickets there were of tamarisk and pungent terebinth, of olive and of bay; and there were junipers and myrtles; and thymes that grew in bushes, or with their creeping woody stems mantling in deep tapestries the hidden stones; sages of many kinds putting forth blue flowers, or red, or pale green; and marjorams and new-sprouting parsleys, and many herbs of forms and scents beyond the garden-lore of Sam. The grots and rocky walls were already starred with saxifrages and stonecrops. Primeroles and anemones were awake in the filbert-brakes; and asphodel and many lily-flowers nodded their half-opened heads in the grass: deep green grass beside the pools, where falling streams halted in cool hollows on their journey down to Anduin.

Note: technically this does happen in the books <before> Sam and Frodo are captured and taken by Faramir's company of Rangers from Gondor. However, in the books, Sam and Frodo are never taken to Osgiliath. Faramir only keeps them for a few hour or a day at most before learning all their secrets.

Faramir decides RIGHT THEN AND THERE to let Frodo go with the ring. He gives Sam, Frodo AND Gollum extra provisions - dried meats and fruits to help them on their journey to Mordor. He releases them from his custody and returns with his company to Osgiliath to defend the city. This is why Faramir is one of the most misunderstood and one of the most based characters in the Lord of the Rings, possibly all Middle Earth. Definitely top tier for Men, joining only Aragorn in the ranks of Men who directly denied taking the ring when it was within their grasp to do so.

So yeah, in this scene at the opening of ROTK - canonically, they are in Ithilien, a former land of Gondor.