timotaka: I was wondering the same, but eventually I realized that it is the inventory icon for money, and checking my inventory confirmed it. The game gradually gives you a little bit of money every few minutes at least when playing as the Bachelor. I have no idea why.

edit: Apparently what this is supposed to mean is your character happens to come across coins lying on the ground and picks them up. You can also come across other minor items just walking around, such as needles. I've also come across nuts when walking outside the town.