Cream the butter; add the sugar and beat until light. Blend in the eggs and sour cream. Sift the flour with the baking soda and salt, then mix in the poppy seed.
Add to the first mixture and combine thoroughly. Chill the dough for easier handling. Roll the dough thin and cut with a floured cookie cutter. Place on a greased baking sheet and bake in a moderate oven (375 degrees F.) until delicately browned.