The color you use for background (and foreground) to your still life should be something that enhances the subject, that makes it stand out, not something that competes for the viewer's attention. I would start by considering the complementary color to the dominant color in the subject, then an analogous color.
Create the background or backdrop by draping a piece of fabric (an item of clothing works well too) over something taller than your still life arrangement, or peg it to something. Don't worry about creases in the fabric -- enhance it to create visual intrigue in the background, use artistic license to leave it out, or abstract the changes in tone to create gentle variation in the background.
