Melt 3 tablespoons of the butter in large skillet over medium heat. Add onion; cook and stir 2 to 3 minutes or until softened. Add tarragon and mushrooms; cook about 7 minutes or until mushrooms are tender and begin to release liquid, stirring occasionally. Remove mushrooms and juices from skillet; set aside.
Melt remaining 3 tablespoons butter in same skillet over medium-low heat. Add chicken livers; cook 8 to 10 minutes or until thoroughly cooked. Add wine; cook an additional 2 minutes. Cool 15 minutes or until completely cooled.
In food processor bowl with metal blade, combine cooked mushrooms with juices, chicken livers with cooking liquid and almonds; pulse until pureed.
Add sour cream and salt; pulse to combine. Spoon mixture into terrine or serving bowl. Sprinkle with parsley. Cover; refrigerate at least 1 hour to blend flavors. Serve with assorted crackers.