Heat oven to 375 degrees F. On a lightly floured board, roll out the pastry dough 1/ 16-inch thick.
Using a 3-inch cutter, cut out 42 circles, re-rolling scraps as needed. Fit circles into bottoms and slightly up sides of lightly-greased, 2 1/2-inch muffin pans. Meanwhile, fry bacon slices until crisp, drain on paper towel; crumble or chop. Chop mushrooms and saute in butter until they are limp and the liquid evaporates.
Combine bacon, mushrooms, green onion and cheese. Divide filling equally among muffin cups. In large bowl, beat eggs, add sour cream, and stir until smooth. Spoon about 1 tablespoon into each muffin cup.
Bake until puffed and light brown, 20-25 minutes. Cool in pan 5 minutes; lift out. Serve warm or let cool on wire racks.