Sow a few rows of colourful carrots.
Carrots will fork or bifurcate if they hit stones, sticks or other obstacles, so cultivate your soil to a fine tilth before you sow and if you have heavy clay, dig in sand or gypsum. Carrot seed is tiny, so either over-sow and thin when the seedlings appear or mix a pinch of seeds with a couple of teaspoons of sand then sprinkle it along the row. Even easier, use a seed tape. The seeds are prespaced so you just bury the tape!