“Fer felt something pulling at her from that other place, something she felt in her bones. Her father had said she belonged there. Maybe she did. And she had a story without an ending pulling at her too.”
Winterling by Sarah Prineas has a fairly standard GU plot, albeit not a particularly riveting one in my opinion. Fer (short for Jennifer) lives with her grandmother, having lost both her parents mysteriously when she was a baby. One day she runs from the house to avoid her grandmother’s restrictive rules, only to come upon a boy (who might also be a dog) being attacked by wolves in the forest. She soon discovers that the boy and the wolves have come through the Way from another world, a world that she herself is tied to via her mother.
Fer insists on journeying to the otherworld to find out what happened to her parents. Once there she is immediately welcomed by a great Lady called the Mor, and has the dog-boy (Rook) as her reluctant companion. However, the Mor is evil, and when her attempts to corrupt Fer (a common theme with the adversary) fail, she tries to use her as a sacrifice instead.
Fer returns home briefly in the middle of her adventure (another common theme) but feel compelled to go back to the otherworld to defeat the Mor and help bring spring back to all the lands. On that quest, she does briefly go literally underground to find the Leaf Woman who can help change the seasons. She rather easily defeats her weakened adversary, and discovers she is More than she ever expected.