Preheat the oven to 425F.
In a medium bowl, whisk together the flour, sugar, baking powder and salt. Add the cream and vanilla and start to stir; add the rhubarb and stir just until the dough comes together.
Gather it up into a ball, getting any dry bits up out of the bowl with your hands. Fold it over itself a couple times as you gather it up, and pat into a 1-inch thick circle on a parchment-lined baking sheet.
If you like, brush the top with a bit of cream - I usually have enough left in the bottom of the measuring cup - and sprinkle with sugar. Cut into 6-8 wedges with a sharp knife, and pull the scones apart so that they have room to brown. Bake for 15-20 minutes, or until golden.