1Dissolve yeast in ½ cup warm water and let stand 5 minutes. In a large bowl, combine yeast mixture, 1 ½ cups warm milk, 2 cups of sweet potato's, ½ cup butter, ½ cup sugar, and ½ teaspoon salt. Mix well. Stir in 2 slightly beaten egg and ½ cup flour. Cover with a towel, plastic wrap, or aluminum foil, and let rise in a warm place, free from drafts for 30 minutes. after 30 min batter will look spongy. Gradually stir in enough of the remaining flour to make a soft dough. Cover and let rise in a warm place 1 hour, or until dough is doubled in bulk. Kneed dough down. Take a significant amount , form into a ball and begain to shape and make small ball shapes by pinching your thumb and pointer fingers to gather and drop a roll about 2 to 2.5 inches in diameter. On to a greased baking sheet and let rise in a warm place 20 minutes, or until dough is doubled in bulk. Bake at 400 degrees for 10 minutes, or until golden brown. This makes 4 dozen drop rolls. When you have your rolls shaped and placed in pans, you may cover and refrigerate or freeze them for later use. All you have to do is get them out of the refrigerator or freezer, let them come to room temperature, and then let them rise for 15-20 minutes before baking. Enjoy & Happy Holidays!