Here's the recipe for a good sweet potato pie - only changes I made was to add a pinch of ginger and cut the sugar to a scant 1/2 cup:
The recipe is from our cookbook Pie Every Day by Pat Willard (she says she cobbed it from Sheila Ferguson's Soul Food).
Anyway, cut down on the sugar for a tastier pie. I used two different sweet potatoes: about 1/2 long ruby potatoes and 1/2 squatter golden or orange tubers.
That's not necessary - any commonly sold yam or sweet potato will suffice to make a delicious pie.
Here's the way the completed pie looked: