This one comes from my great aunt Ada who lived in Indiana, PA. She had a
rhubarb patch growing out back. I remember her kitchen door was one of
those double-dutch doors

And she never relinquished her big old cast
iron stove. Note there is no mention of "crumbs" until you get to the part
where you bake this... so I have no idea what she meant or how much to use.
Rhubarb Crunch
Mix together:
1 c. brown sugar
3/4 c. quick oatmeal
1 c. flour
1 tsp. cinnamon
1/2 c. melted butter or shortening
2 Tbs. cornstarch
1 c. white sugar
1 c. water
vanilla
Dice 3 cups rhubarb
Cook until thick. Put half crumbs in a greased baking dish, 8X9 square.
Put rhubarb on top of crumbs. Then pour boiled misture over the rhubarb and
top with remaining crumbs. Bake at 350 until done, about 1/2 hour.
Jill