The one thing I have noticed that there seems to be a growing prevalence of small gifts or favours that hosts give to guests on departure. This is very common at baby showers and young children's birthday parties and I have seen them at American wedding rehearsal diners and engagement lunches. Many corporate events also give attendees a gift - usually themed or branded with the company logo.
This idea works really well for an event where you are providing a large-ish number of the same item. It works best with small items and can be used on dried food items such as candy/sweets.
Paper napkins a ideal for this purpose. They are all the same size and usually come in packs of 20+. The great thing is if you want them all to be identical they can be or you can mix up colours and patterns to suit your requirements. Most supermarkets stock a wide range of paper napkins as does John Lewis and party shops.
I have used paper napkins to wrap small candles, homemade iced gem biscuits and a few years ago I used a cool mouse printed napkin to wrap sugared mice. For items such as chocolates and cookies you can wrap the napkin in cellophane if you think you may require some extra protection.
These napkins would be ideal for Valentines Gifts!