This light blue background pattern is quite pleasing to the eye, it consists of a tiny rough grid pattern, which is seamless by design. That's it, if you like the color, you can use this seamless pattern in a web design without making any further modifications to it.
Source V. Hartikainen
A comeback for you: the popular Escheresque, now in black.
Source Patten
A seamless pattern formed from a square tile. To get the tile, select the rectangle in Inkscape and use shift+alt+i.
Source Firkin
Number 3 in a series of 5 beautiful patterns. Can be found in colors on the submitter’s website.
Source Janos Koos
Everyone loves a diamond, right? Make your site sparkle.
Source AJ Troxell
A seamless texture traced from an image on opengameart.org shared by Scouser.
Source Firkin
Zero CC asphalt, pavement, texture, photographed and made by me. CC0 WARNING I FOUND A SEAM ON THIS TEXTURE
Source Sojan Janso
The tile this is based on can be retrieved by selecting the rectangle in Inkscape and using shift+alt+i.
Source Firkin
Pattern Background, Texture, Photoshop Structure style CC0 texture.
Source Darkmoon1968
Light square grid pattern, great for a “DIY projects” sort of website, maybe?
Source Rafael Almeida
A seamless pattern formed from a square tile. The tile can be retrieved by selecting the rectangle in Inkscape and using shift-alt-i.
Source Firkin
Floral patterns will never go out of style, so enjoy this one.
Source Lasma
I’m guessing this is related to the Sony Vaio? It’s a nice pattern no matter where it’s from.
Source Zigzain
A new take on the black linen pattern. Softer this time.
Source Atle Mo
Colorful Floral Background No Black
Source GDJ
Sweet and subtle white plaster with hints of noise and grunge.
Source Phil Maurer
To get the tile this is based on, select the rectangle in Inkscape and use shift+alt+i.
Source Firkin
Recreated from a pattern found in 'Az Osztrák-Magyar Monarchia irásban és képben', 1882. To get the tile this is based on select the rectangle in Inkscape and use shift+alt+i.
Source Firkin
From a drawing in 'Danmarks Riges Historie af J. Steenstrup, Kr. Erslev, A. Heise, V. Mollerup, J. A. Fridericia, E. Holm, A. D. Jørgensen', 1897.
Source Firkin
From a drawing in 'Worsborough; its historical associations and rural attractions', Joseph Wilkinson, 1879.
Source Firkin
Prismatic Abstract Geometric Background 5
Source GDJ
Bigger is better, right? So here you have some large carbon fiber.
Source Factorio.us Collective
The image depicts a seamless pattern of pine tree leaves.
Source Yamachem
A free seamless background texture that looks like a brown stone wall.
Source V. Hartikainen
White little knobs, coming in at 10x10px. Sweet!
Source Amos
CC0 and a seamless pattern from a tile drawn in Paint.net .
Source SliverKnight