Flowers are pricey and die after a few days. Why would you want to give her anything that was about to perish. Maybe she would also like day old doughnuts, or a really sick puppy.
Save the purchase of anything flower like for when you have done something really terrible. The surprise of flowers will throw her off the scent that something is awry. You could even put a card in there with a few token words. Best to ask the gal at the flower store to write something up, as she has likely done it many times before and can certainly be more poetic that yourself.