From a drawing in 'A Guide to the Guildhall of the City of London', John Baddeley, 1898.
Source Firkin
Tiny little fibers making a soft and sweet look.
Source Badhon Ebrahim
Tiny, tiny 3D cubes. Reminds me of the good old pattern from k10k.
Source Etienne Rallion
Embossed lines and squares with subtle highlights.
Source Alex Parker
From a drawing in 'Sun Pictures of the Norfolk Broads', Ernest Suffling, 1892.
Source Firkin
White fabric looking texture with some nice random wave features.
Source Hendrik Lammers
Retro Circles Background 7 No Black
Source GDJ
Seamless , tileable CC-0 texture. Created by my own, feel free to use wherever you want!
Source Linolafett
A seamless texture traced from an image on opengameart.org shared by Scouser.
Source Firkin
Could remind you a bit of those squares in Super Mario Bros, yeh?
Source Jeff Wall
Seamless , tileable CC-0 texture. Created by my own, feel free to use wherever you want!
Source Linolafett
Square design drawn in Paint.net and vectorized in Vector Magic.
Source Firkin
Zero CC tileable ground (#2) cracked, crackled texture, made by me. CC0
Source Sojan Janso
This is a semi-dark pattern, sort of linen-y.
Source Sagive SEO
A rusty grunge background for websites. Feel free to use it in your site's theme.
Source V. Hartikainen
You guessed it – looks a bit like cloth.
Source Peax Webdesign
Prismatic Snowflakes Pattern 2 No Background
Source GDJ
A seamless pattern the unit cell for which can be had by selecting the rectangle in Inkscape and using shift+alt+i.
Source Firkin