You don’t see many mid-tone patterns here, but this one is nice.
Source Joel Klein
ZeroCC tileable wood boards texture, photographed and made by me. CC0
Source Sojan Janso
All good things come in threes, so I give you the third in my little concrete wall series.
Source Atle Mo
From a drawing in 'Picturesque New Guinea', J Lindt, 1887.
Source Firkin
The image a seamless pattern of a wire-mesh fence.I want you to use this pattern as a lower layer.
Source Yamachem
The unit cell for this seamless pattern can be had in Inkscape by selecting the rectangle and using shift+alt+i.
Source Firkin
Like the name suggests, this background image consists of a pattern of dark bricks. It may be an option for you, if you are looking for something that looks like a brick wall for use as a background on web pages. It's not a masterpiece, but looks pretty nice when is tiled.
Source V. Hartikainen
Prismatic Groovy Concentric Background 2 No Black
Source GDJ
Colorful Floral Background No Black
Source GDJ
Background formed from the original with an emboss effect
Source GDJ
Paper pattern with small dust particles and 45-degree strokes.
Source Atle Mo
Seamless , tileable CC-0 texture. Created by my own, feel free to use wherever you want!
Source Linolafett
Light gray grunge wall with a nice texture overlay.
Source Adam Anlauf
A light gray wall or floor (you decide) of concrete.
Source Atle Mo
To get the tile this is based on, select the rectangle in Inkscape and use shift-alt-i.
Source Firkin
This seamless background image should look nice on websites. It has a dark blue gray texture with vertical stripes, it tiles seamlessly and, like all of the background images here, it's free. So, if you like it, take it!
Source V. Hartikainen
Prismatic Hexagonalism Pattern No Background
Source GDJ