Daja's Book (Circle of Magic, #3)

There is an alternate cover edition here.

Outcast Trader Daja, along with her fellow mages-in-training, journeys from Winding Circle to the Gold Ridge Mountains, where drought threatens widespread famine. There, Daja creates an astonishing object: a living metal vine, and Daja's dealings with her former people reawaken a longing for familiar ways.

Daja must choose - should she return to the Traders or remain with the Winding Circle folk who have become her family?