I really enjoy the Ghoul coins/Holiday coins idea, so id love to see seasonal coins.
Season Coins could be coins that change every 3 months depending on the season. With these coins, You can buy Season-related items at a shop, these could be brand new items each season, or swap between them.
Items could include for example a Flower patch for spring, a Sun shaped bed lamp for Summer, leaf blowers for fall, and or ear muff cosmetics for winter. These are just ideas but ofcourse there should be more than one item.