This is the gal who young Dunstan Thorn has a crush on. She's described as "a young woman of similar practicality" (1.40). Dunstan's courtship strategies reflect this: "They would walk, on fair evenings, around the village, and discuss the theory of crop rotation, and the weather, and other such sensible matters" (1.40).
Daisy's female family members chaperone them on these dates, and they listen to Daisy complain about why Dunstan seems to be taking a while to propose. At the Faerie Market, Dunstan brings her the glass snowdrop as a gift, which she accepts, "puzzled" (1.156). He impulsively kisses her, which causes her "to be smiling through her tears" (1.160), but then things go downhill from there.
A few weeks after the market, Daisy's mom complains to Dunstan's mom that Daisy is wasting away for lack of attention from Dunstan: "'She does not eat, Mrs. Thorn. She wastes away. She drinks a little water from time to time'" (1.209). But the matchmaking moms prevail, and Daisy and Dunstan are wed soon after.
Daisy isn't too fond of Tristran when he shows up, though Tristran has no clue why: "Sometimes Tristran would look up to see his mother staring at him intently, as if she were trying to tease some secret from his face" (2.7). At least she packs Tristran a bag of food when he sets off for Faerie, though she "would not look at Tristran" (2.116) as he leaves. We're guessing she has mixed feelings about seeing him go. He's not her biological son, after all, and she didn't seem to have a choice about whether to raise him.