Here I have tried to create something that would look like maple wood. Not sure how well it's turned out, but at least it looks like wood.
Source V. Hartikainen
Used correctly, this could be nice. Used in a bad way, all hell will break loose.
Source Atle Mo
Seamless pattern the tile for which can be had by using shift-alt-I on the selected rectangle in Inkscape.
Source Firkin
Same as the black version, but now in shades of gray. Very subtle and fine grained.
Source Atle Mo
Derived from a corner decoration itself found as a jpg on Pixabay.
Source Firkin
Bigger is better, right? So here you have some large carbon fiber.
Source Factorio.us Collective
Adapted from a drawing in 'Line and form', Walter Crane, 1914.
Source Firkin
Because I love dark patterns, here is Brushed Alum in a dark coating.
Source Tim Ward
This seamless light brown background texture resembles a wallpaper with vertical stripes. One way to use it is as a tiled background on web sites.
Source V. Hartikainen
A repeating background of beige (or is it more vanilla yellow) textured stripes. One more background with stripes.
Source V. Hartikainen
Small gradient crosses inside 45-degree boxes, or bigger crosses if you will.
Source Wassim
Honestly, who does not like a little pipe and mustache?
Source Luca Errico
Sort of like the Photoshop transparent background, but better!
Source Alex Parker
Prismatic Groovy Concentric Background 4
Source GDJ
Have you wondered about how it feels to be buried alive? Here is the pattern for it.
Source Hendrik Lammers
A seamless texture of an abstract wall colored in shades of light orange brown.
Source V. Hartikainen
Made by distorting a simple pattern using the 'sin waves' plugin for Paint.net and vectorising in Vector Magic
Source Firkin
A seamless pattern from a tile made from a jpg on Pixabay. To get the tile select the rectangle in Inkscape and use shift-alt-i.
Source Firkin
To get the tile this is based on select the rectangle in Inkscape and use shift+alt+i.
Source Firkin
Wasn't satisfied with the original's colouring. Too much component transfer and colormatrixes yet the results are lacking a bit. So this time it is a simple black to transparent fade, making it possible remixing easily once there will be other blending modes supported as well. Probably in inkscape 0.92.
Source Lazur URH