Stock
Stock or Matthiola are one of my very favourite spring flowers! They are reasonably quick to flower and will flower in winter if planted early enough!
Stock are cool loving flowers, preferring the cool of winter over the heat of summer, so are best sown from autumn through to mid-spring. You can also sow them late summer for autumn flowers, though this can be a little tricky due to the heat and the fact they're part of the brassica family so white butterflies and their hungry caterpillars absolutely love them!