Wild Maine blueberries are delicious. You can find them out of season in the frozen food section, and they work perfectly for this recipe.
The first time I had a similar muffin was visiting family friends in Maine one summer. We picked so many wild blueberries that we made muffins and pie! That was the beginning of my love affair with wild blueberries.
You can certainly use regular blueberries if you cannot find wild blueberries. Keep the amount the same because adding more will change the moisture content of the muffins.