A seamless pattern based on a rectangular tile that can be retrieved in Inkscape by selecting the rectangle and using shift-alt-i.
Source Firkin
Some rectangles, a bit of dust and grunge, plus a hint of concrete.
Source Atle Mo
Zero CC tileable pine bark texture, photographed and made by me. CC0
Source Sojan Janso
The original enhanced with one of Inkscapes's filters.
Source Firkin
The tile this is based on can be retrieved by selecting the rectangle in Inkscape and using shift+alt+i.
Source Firkin
The unit cell for this seamless pattern can be had in Inkscape by selecting the rectangle and using shift+alt+i.
Source Firkin
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
Prismatic Geometric Pattern Variation 2 With Background
Source GDJ
As simple and subtle as it gets. But sometimes that’s just what you want.
Source Designova
A seamless pattern the unit cell for which can be had by selecting the rectangle in Inkscape and using shift+alt+i
Source Firkin
From a drawing in 'From Snowdon to the Sea. Striking stories of North and South Wales', Marie Trevelyan, 1895.
Source Firkin
Dark blue concrete wall with some small dust spots.
Source Atle Mo
A seamless texture traced from an image on opengameart.org shared by Scouser.
Source Firkin
The classic notebook paper with horizontal stripes.
Source Are Sundnes
A seamless pattern formed from miutopia mug remixes on a tablecloth.
Source Firkin
An orange vertically striped background pattern. Feel free to download and use this orange background pattern, for example, on the web). It resembles a wallpaper with vertical stripes or something similar to it.
Source V. Hartikainen
People seem to enjoy dark patterns, so here is one with some circles.
Source Atle Mo
Number 4 in a series of 5 beautiful patterns. Can be found in colors on the submitter’s website.
Source Janos Koos
Looks like a technical drawing board: small squares forming a nice grid.
Source We Are Pixel8
A rusty grunge background for websites. Feel free to use it in your site's theme.
Source V. Hartikainen