Here's a subtle marble-like background for use on websites.
Source V. Hartikainen
This one needs to be used in small areas; you can see it repeat.
Source Luca
A seamless dark leather-like background texture with diagonal lines that look like stitches.
Source V. Hartikainen
A free background tile with a pattern of pink bump dots. This background tile is sweet! Moreover, it's designed for use as website backgrounds.
Source V. Hartikainen
A seamless pattern formed from a modified version of rwwgub's tile. To get the tile, select the rectangle in Inkscape and use shift+alt+i.
Source Firkin
Prismatic Hypnotic Pattern No Background
Source GDJ
The tile this is formed from can be retrieved in Inkscape by selecting the rectangle and using shift+alt+i
Source Firkin
A rusty grunge background for websites. Feel free to use it in your site's theme.
Source V. Hartikainen
A pale orange background pattern with glossy groove stripes.
Source V. Hartikainen
A seamless texture traced from an image on opengameart.org shared by Scouser.
Source Firkin
Seamless pattern made from a tile that can be obtained in Inkscape by selecting the rectangle and using shift+alt+i.
Source Firkin
The tile this is formed from can be retrieved in Inkscape by selecting the rectangle and using shift+alt+i
Source Firkin
This is indeed a bit strange, but here’s to the crazy ones!
Source Christopher Buecheler
A seamless pattern formed from a tile made from page ornament 22. To get the tile, select the rectangle in Inkscape and use shift+alt+i.
Source Firkin
These dots are already worn for you, so you don’t have to.
Source Matt McDaniel
Derived from a PNG that was uploaded to Pixabay by nutkitten
Source Firkin
A free background image with a seamless texture of cardboard. This texture of cardboard looks quite realistic, especially when is actually tiled.
Source V. Hartikainen
Prismatic Rounded Squares Grid 4 No Background
Source GDJ
A pale olive green background with a seamless texture.
Source V. Hartikainen
A topographic map like this has actually been requested a few times, so here you go!
Source Sam Feyaerts
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
CC0 and a seamless pattern from a tile drawn in Paint.net .
Source SliverKnight