I Found the Entwives!

[Ardent]

This is from the song of the Entwives:

When spring is come to garth and field, and corn is in the blade;
When blossom like a shining snow is on the orchard laid;
When shower and Sun upon the Earth with fragrance fill the air,
I'll linger here and will not come, because my land is fair.

Fragrance fills the air in Ithilien, but the general type of trees are not orchard species, and the trees at the crossroads are far too large to fit the type described by Treebeard:

"But the entwives gave their minds to the lesser trees, and to the meads in the sunshine beyond the feet of the forest; and they saw the sloe in the thicket... and the green herbs in the waterlands... and bear leaf and fruit..."

I do not know of any reason to suppose the Entwives were even 'treeish'. Though they had "the eyes of our people" they also had hair parched by the sun. This is why I'm not inclined to think the sighting of a tree that walked in The Shire was an Entwife. Though we're told they would like the Shire this sounds more like a searching Ent.
Considering their love of fruit and corn and watermeadow, and their golden hair, and the structure of Entish names (in our language at any rate) I would say that Goldberry fits the bill.

While this is my favoured view, I'm still glad that there is no explicit statement of 'here be an Entwife'. Even if there were such a comment from JRRT it would still raise the question of where the rest had gone, and it's much more fascinating to think Goldberry might be some other being like a Maiar or a fair young elf queen.