A smooth mid-tone gray, or low contrast if you will, linen pattern.
Source Jordan Pittman
Seamless pattern formed from a tile that can be had by selecting the rectangle in Inkscape and using shift-alt-i.
Source Firkin
A seamless background texture of old cardboard.
Source V. Hartikainen
From a drawing in 'Navigations de Alouys de Cademoste.-La Navigation du Capitaine Pierre Sintre', Alvise da ca da Mosto, 1895.
Source Firkin
A seamless pattern the starting point for which was a 'rainbow twist' texture in Paint.net.
Source Firkin
If you want png files of this u can download them here : viscious-speed.deviantart.com/gallery/27635117
Source Viscious-Speed
Prismatic Geometric Pattern Background No Black
Source GDJ
One more in the line of patterns inspired by Japanese/Asian styles. Smooth.
Source Kim Ruddock
Fabric-ish patterns are close to my heart. French Stucco to the rescue.
Source Christopher Buecheler
From a drawing in 'Line and form', Walter Crane, 1914.
Source Firkin
To get the tile this is based on, select the rectangle in Inkscape and use shift-alt-i.
Source Firkin
Looks like a technical drawing board: small squares forming a nice grid.
Source We Are Pixel8
A smooth mid-tone gray, or low contrast if you will, linen pattern.
Source Jordan Pittman
A pale olive green background with a seamless texture.
Source V. Hartikainen
With a name like this, it has to be hot. Diagonal lines in light shades.
Source Isaac
Drawn in Paint.net and vectorised in Vector Magic
Source Firkin
Dark wooden pattern, given the subtle treatment. based on texture from Cloaks.
Sweet and subtle white plaster with hints of noise and grunge.
Source Phil Maurer
Zerro CC tillable texture of stones photographed and made by me. CC0
Source Sojan Janso
Some more diagonal lines and noise, because you know you want it.
Source Atle Mo
Background Wall, Art Abstract, Watercolor Vintage style CC0 texture.
Source Ractapopulous