Have you got a theme that is running through the rest of the wedding? Colours etc?
Also, you could theme the favour depending on where you are gettting married - for example if its by the seaside, how about a stick of rock. If it's in Devon, how about a small bag of Devon fudge.
You can get Love Heart sweets in small packets, specifically for weddings. A lottery ticket per person? You can get what look like a pack of matches, but each stick is impregnated with flower or herb seeds.
I would suggest something the guest can eat or use, as you will end up spending money on something that could well end up in the back of a drawer.