Black brick wall pattern. Brick your site up!
Source Alex Parker
To get the tile this is based on, select the rectangle in Inkscape and use shift+alt+i.
Source Firkin
Prismatic Groovy Concentric Background 2 No Black
Source GDJ
A seamless texture traced from an image on opengameart.org shared by Scouser.
Source Firkin
If you want png files of this u can download them here : viscious-speed.deviantart.com/gallery/27635117
Source Viscious-Speed
From a drawing in 'Navigations de Alouys de Cademoste.-La Navigation du Capitaine Pierre Sintre', Alvise da ca da Mosto, 1895.
Source Firkin
Simple gray checkered lines, in light tones.
Source Radosław Rzepecki
Prismatic Geometric Tessellation Pattern 2 No Background
Source GDJ
Zero CC tileable dry grass texture, photographed and made by me. CC0
Source Sojan Janso
Seamless pattern formed from a tile that can be had by selecting the rectangle in Inkscape and using shift-alt-i.
Source Firkin
This was formed by distorting an image of a background on Pixabay.
Source Firkin
This reminds me of Game Cube. A nice light 3D cube pattern.
Source Sander Ottens
Zero CC tileable moss or lichen covered stone texture, edited from pixabay. CC0
Source Sojan Janso
From a drawing in 'At home', J. Sowerby, J. Crane and T. Frederick, 1881.
Source Firkin
Prismatic Curved Diamond Pattern 3 No Background
Source GDJ
An abstract web texture of a polished blue stone (or does it look more like ice).
Source V. Hartikainen
A mid-tone gray pattern with some cement looking texture.
Source Hendrik Lammers
A pale yellow background pattern with vertical stripes. The stripes are partially faded. I think this background image turned out pretty well, especially those faded stripes.
Source V. Hartikainen
Prismatic Isometric Cube Wireframe Pattern No Background
Source GDJ
Background formed from the original with an emboss effect
Source GDJ
White circles connecting on a light gray background.
Source Mark Collins
A dark striped seamless pattern suitable for use as a background on websites.
Source V. Hartikainen