From a tile that can be had by selecting the rectangle in Inkscape and using shift+alt+i.
Source Firkin
A beautiful dark wood pattern, superbly tiled.
Source Omar Alvarado
A pattern derived from repeating unit cells each derived from part of a fractal rendering in paint.net.
Source Firkin
Embossed lines and squares with subtle highlights.
Source Alex Parker
This one resembles a black concrete wall when is tiled. It should look great, at least with dark website themes.
Source V. Hartikainen
A pattern formed from a squared tile. The tile can be accessed in Inkscape by selecting the rectangle and using shift-alt-i.
Source Firkin
This is so subtle I hope you can see it! Tweak at will.
Source Alexandre Naud
Remix from a drawing in 'Ostatnie chwile powstania styczniowego', Zygmunt Sulima, 1887.
Source Firkin
Prismatic Groovy Concentric Background 5 No Black
Source GDJ
One more brick pattern. A bit more depth to this one.
Source Benjamin Ward
A seamless pattern with green and yellow diagonal lines on top of a white dotted background.
Source V. Hartikainen
You know you can’t get enough of these linen-fabric-y patterns.
Source James Basoo
Same as Silver Scales, but in black. Turn your site into a dragon with this great scale pattern.
Source Alex Parker
A seamless light gray paper texture with horizontal double lines.
Source V. Hartikainen
Love the style on this one, very fresh. Diagonal diamond pattern. Get it?
Source INS
Drawn in Paint.net and vectorised in Vector Magic.
Source Firkin
Seamless Dark Grunge Texture. Here's a new grunge texture for use as a background.
Source V. Hartikainen
One of the few full-color patterns here, but this one was just too good to pass up.
Source Alexey Usoltsev
Zero CC tileable ground (#2) cracked, crackled texture, made by me. CC0
Source Sojan Janso
Black brick wall pattern. Brick your site up!
Source Alex Parker
Formed by distorting the inside front cover of 'Diversæ insectarum volatilium : icones ad vivum accuratissmè depictæ per celeberrimum pictorem', Jacob Hoefnagel, 1630.
Source Firkin
Remixed from a JPG that was uploaded to Pixabay by theasad121
Source Firkin