After stressful days. Also "Just because." And when I have to meet an important deadline and work on something it's nice to have fresh flowers to work beside.
Flowers are always a treat to me :) But occasionally my parents would send me flowers during finals week, or just during really stressful times in my life and it always made me feel really happy and loved.
And daffodils because the deer around my house eat just about anything but daffodils.