If you have an indoor dog, you need a dog bed. My dog has traditionally had access to our bed, and for many years showed little interest in her dog bed. Perhaps it was not what she preferred. It had three sides, and one low side for easy access, but the bottom was flat, with no stuffing. There was a matching pillow, but she would move her pillow about and it would rarely be in her bed. So, she was essentially on the hard floor with a couple of pieces of cloth providing little cushion.
Today, she has a new bed, and my old dog loves it. The bottom is padded, and there are three high sides with a lower side. She fits nicely, and sometimes uses a side as a pillow. The lower side allows her to enter and exit easier, which gets more important with age. This bed is her favorite place.