I contacted Dollar Tree stores in Michigan, North Carolina, Texas, and Utah to confirm that third-party gift cards aren’t available at the retailer. All of the representatives I spoke with confirmed that you can’t buy third-party gift cards.
However, Dollar Tree’s own gift cards are available in stores and online for any amount between $5 and $100.
Dollar Tree also sells Green Dot reloadable cards, but these are prepaid debit cards, not gift cards.
For an alternative that’s suitable for gifts, see my research on where to buy Visa gift cards.