I suggest that you choose a plain white, or off-white, background for the main content area of your site.

Paper or cardboard effect textures could work well as backgrounds in smaller areas, such as the header, footer or other sections of the page.

Here are some free suggestions from

A lightened version of Paper by Blaq Annabiosis

Light Paper Fibres by Jorge Fuentes

Rice Paper 2 by Atle Mo

Handmade Paper by Le Marquis

Other backgrounds to consider include:

You could also consider using a hand-drawn seamless pattern as the background to a site with a boxed layout (pattern on either side of the central content box).