The classic subtle pattern. Sort of wall/brick looking. Or moon-looking?
Source Joel Klein
Seamless pattern the basic tile for which can be had by selecting the rectangle in Inkscape and using shift+alt+i.
Source Firkin
Plywood Web Background background image for use in web design.
Source V. Hartikainen
You know you can’t get enough of these linen-fabric-y patterns.
Source James Basoo
You don’t see many mid-tone patterns here, but this one is nice.
Source Joel Klein
Detailed but still subtle and quite original. Lovely gray shades.
Source Kim Ruddock
Zero CC Mossy stone tileable texture, photographed and made by me. CC0
Source Sojan Janso
Here's a repeatable texture that resembles a light green concrete wall or something similar.
Source V. Hartikainen
Beautiful dark noise pattern with some dust and grunge.
Source Vincent Klaiber
Zerro CC tillable texture of stones photographed and made by me. CC0
Source Sojan Janso
Brushed aluminum, in a bright gray version. Lovely 2X as well.
Source Andre Schouten
This light background pattern has a texture of "frozen" surface with diagonal stripes. Here's an yet another addition to the collection of free website backgrounds.
Source V. Hartikainen
Remixed from a drawing in 'Maidenhood; or, the Verge of the Stream', Laura Jewry, 1876.
Source Firkin