Halloween is tomorrow, and there is still time to grab a few funky pumpkins or pretty squashes before the farm stands disappear. Making a pumpculent (pumpkin/succulent) centerpiece is easy, and since you don't cut into the pumpkin, it will last as long as all the way to next summer, when you can transplant your succulents to something a bit more seasonal.
If done right, the succulents (which aren't just propped up on the pumpkin) will actually root themselves into the moss beneath and will happily live for many months. Come December, you can change it up and maybe re-use the succulents mixed in with evergreens or giant pine cones. In the spring you might consider transplanting them into an arrangement that features rocks, moss and bulbs to make a springy mix. When summer comes around again, plant them outside where they will grow, and many will make babies which can be harvested for use next year's arrangements.