The speaker has just woken from a dream in which someone spoke to them, and the dream is already slipping away. As the voice fades, it turns into the song of a wood thrush, as if the dream were dissolving into the real morning outside. Caught between sleep and waking, the speaker asks the unanswered question "who are you," addressed to the vanishing figure, and perhaps to the voice itself.
The last two lines shift from mystery to something small and physical. The speaker pulls the comforter up over the tangled blankets, a gesture that suggests a wish to stay in warmth and half-sleep, maybe to hold on to the dream a little longer. The tangled bedding also hints at a restless night. The mood is quiet, tender, and a bit wistful. There is longing for someone or something that can't be named, but the poem doesn't turn it into grief. It simply lets the feeling linger, like the last moments before the day takes over.