There is a greenmarket in front of my office twice a week. I love checking it out to see what's in season. When I can, I prefer to buy from them. I love the splashes of color from the stands as I walk out of the subway. It's a nice change from the shlock vendors that stand in its place during the rest of the week.
Mix up the sliced rhubarb with the white sugar and the flour. Place in a buttered baking dish. A 9x9 would work for this.
Bake until the topping is golden brown. The rhubarb should be soft. It should take around 30-35 minutes.
Serve while warm - with a nice scoop of ice cream. Enjoy!