Great question — answering as the UphillTech team:
You described this material as "like a garland but smaller," and Google results for "miniature (pine) garland" seem to return exactly what you're looking for. If you specifically want to make dollhouse wreaths, you can look for "artificial Christmas garland ties," which are precut to the size of large twist-ties and made of stiff wire. Some of them should be approximately the correct width and length for a dollhouse wreath, but check the exact product for details.
Full answer by Esther: https://crafts.stackexchange.com/a/11311 (CC BY-SA 4.0).
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