Any flat surface will work to a greater or lesser degree. A white bedsheet can be used if you want a light background. A piece of plywood painted to your taste can serve as well. Painting one's own background is a historical discipline in photography. User cjbroadbent, a modern master of still life photography, addresses this nicely on the large format site.
With a high quality background, rendering it in sharp focus is an option. This means placing the subject closer to the background, and/or using a smaller aperture.
Lower quality backgrounds (wrinkled, creased, lint, dusty, strange surface, etc.) are better rendered out of focus, in my view. This means placing the subject farther from the background and/or using a larger aperture. Out of focus backgrounds give a more monotone or uniform effect. Lighting the background can accentuate imperfections in the material, something to consider. When the background is rendered out of focus, this is less of a concern.
The two examples are not strictly either-or. There is a range of possibilities between them. It depends on your desired aesthetic, and materials available.