Mary's Lemon Pie

1 9" pie shell
1/2 c butter - softened
2 c sugar
5 eggs
juice and grated rind of 3 lemons
3 tbs flour

Prepare shell. Cream butter and sugar. Add eggs - beat well. Add lemon juice and rind and flour. Mix well. Bake at 300° for 30 to 40 minutes until set and brown. Serves 8.