I first had rhubarb pie when I was about 6. It was tart and sweet at the same time, also very filling. It is the best rhubarb pie I have ever had. This is the recipe my Grandmother(Nanny) wrote for me.
Cut rhubarb into 1-inch pieces or smaller. Mix sugar and flour together and then mix with rhubarb. Put into bottom pie crust and place top crust over. Brush top crust with milk to make it nice and brown. Bake for 15 minutes at 450 degrees, then reduce heat to 350 degrees for 45 minutes longer.