A t-shirt dress is the perfect comfy item for all seasons and is so versatile. You can wear it as a swim cover up, belted in the summer, with a sweater in fall and spring, or boots and tights in the winter. I have a basic white and a basic black t-shirt dress and they are some of my most-worn items in my closet.
Dress / Forever 21 (similar here)
Sweater / Banana Republic
Purse / Fossil (similar here)
Sandals / American Eagle (similar here)