Mix together flour and salt, cut in shortening, sprinkle with water. Gather dough, press into a ball, and roll out into two 9" circles.
If rhubarb is tender and pink, do not peel. Cut into 1" pieces - 1 pound makes 2 cups. Mix together flour and sugar. Mix lightly through fruit and pour into pastry lined 9" pie plate. Dot with butter. Cover with top crust. Make slits in top and sprinkle with sugar. Lattice top may be used instead.
Bake until crust is nicely browned and juices bubble through slits. Bake 40-50 minutes at 425°F. Serve slightly warm.