Photo: A field of daisies
The History:
In Medieval society dating, and courtship rituals were quite different from that of today. First of all, dating was not something that was taken lightly. If a person was spending time with their intended it was as a means to an end not simply 'hanging out'. It would have also been chaperoned. It was of the utmost importance that honour, virtue and chastity (just to be clear we are talking about virginity) were preserved.
This was because:
A). They would never be alone
B). People would speculate something dishonourable was occurring.
Also at this time the concept of love began to make an appearance in the world of relationships. But, it was not necessary as many people still married for reasons of class, wealth, and finding an 'appropriate' match. Many relationships were arranged at the time.
The Custom:
It was from this historical, and social landscape that the concept of giving coded gifts as symbols of affection arose. Since the couple would not be alone together they could, instead, pass notes and gifts to one another. This allowed for intimacy, privacy, and some degree of secrecy in relationships.Tokens of affection took various forms: actual love tokens, poems, and most notably flowers. The language of flowers (floriography) has existed for thousands of years but was extremely popular in Medieval, and Victorian times. Every flower carried a specific meaning, and books or lists were used to help both the giver and receiver decipher the intended message.
For example:
Daisy - innocence
Ivy - Fidelity
Lavender - Distrust
Lilac - First Love
**Click here for a longer list**
The Verdict: Love it (don't leaf it)

It is simply good manners to show up to a date, or a party with flowers. Or to offer flowers as a sign of congratulations or affection. It does not simply have to be a guy giving a girl flowers. Rather friends, women, parents, etc. taking the time to say 'I care' without actually saying it.