Here are a few games that you can play at your Valentine's party. Some are great for children's parties and some are geared more to adults or teens. Suggestions for prizes might be some homemade cookies or a ribbon for the teams.
Wedding favors are small, inexpensive gifts or souvenirs
that you present to your guests as a way of saying "thank-you
for attending our wedding celebration". It has become customary
to give something in return to your guests that they can keep
as a memory of your special day.
There are some good ideas for Valentine Party favors here also.