Brown, drain, and crumble the breakfast sausage. Set aside.

In a large bowl, mix together flour, sugar, baking powder, baking soda, and salt.

Cut in the shortening using a pastry blender or your fingers until the mixture resembles coarse crumbs.

In a separate bowl, soften the yeast in warm water.

Add the yeast mixture and buttermilk to the dry ingredients.

Mix everything together until just combined.

Add the crumbled sausage to the dough and mix well.

Turn the dough out onto a floured board.

Knead the dough briefly until it comes together.

Roll the dough to a 1-inch thickness, adding more flour as needed to prevent sticking.

Cut out circles using a biscuit cutter or a drinking glass.

Place the biscuits on an ungreased baking sheet.

Bake in a preheated oven at 400°F (200°C) for 20 minutes, or until golden brown.