There have been many different kinds of love tokens handed out by ladies to knights, especially around tournaments.
(Boy, do I wish I had access to some of my books on the topic right now -- they are in a storage locker -- I'll be back with citations later on...)
Beginning in the mid-12th century, women gave their champions pieces of embroidery, sashes, veils, napkins (these were very upscale items in the era), and other small tokens. The idea was that the knight would be seen as upholding the honour and name of a given lady and the lady was seen to have an admirer -- this is all part of the Courtly Love "game" of the High Middle Ages. Another popular token was for the woman to give the knight a sleeve -- this is actually easier than it might seem, as (1) people tended to dress in layers and (2) many women's dresses came with detachable outer sleeves in case of hot or cold weather; indeed, there was a fashion for a while of making all such dresses with
three sleeves, that way you could give one to a knight and still have enough for your dress. Often this sleeve would be wrapped around the knights helmet, sort of like a turban.
Now the knight and the lady might not be married, involved, or engaged at all; this was part of the larger game. Still, by the 14th century, it was nearly unheard of for a knight to enter a serious tournament without some token from a lady, even if he had only met her that day.
I'll get you some more info a bit later.
addendum: You might want to check this article on Courtly Love from the wikipedia -- hardly the last word, but a fun place to start on the topic:
http://en.wikipedia.org/wiki/Courtly_love