Might not be super subtle, but quite original in its form.
Source Alex Smith
This is a seamless pattern which is derived from a flower petal image.
Source Yamachem
Subtle scratches on a light gray background.
Source Andrey Ovcharov
Prismatic Abstract Background Design
Source GDJ
Retro Circles Background 5 No Black
Source GDJ
Remixed from an image on Pixabay, the original having been uploaded by darkmoon1968.
Source Firkin
This texture looks like old leather. It should look great as a background on web pages.
Source V. Hartikainen
All good things come in threes, so I give you the third in my little concrete wall series.
Source Atle Mo
A seamless chequerboard pattern formed from a tile that can be had in Inkscape by selecting the rectangle and using shift+alt+i. Alternative colour scheme.
Source Firkin
A version without colours blended together to give a different look.
Source Firkin
A free repetitive background with a dark concrete wall like texture. This one may be used in dark web site designs.
Source V. Hartikainen
Prismatic Abstract Line Art Pattern Background
Source GDJ
Fix side and a seamless pattern formed from circles.
Source SliverKnight
Small gradient crosses inside 45-degree boxes, or bigger crosses if you will.
Source Wassim
Prismatic Curved Diamond Pattern 4 No Background
Source GDJ
The basic shapes never get old. Simple triangle pattern.
Source Atle Mo
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
A seamlessly tile-able grunge background image.
Source V. Hartikainen
Real snow that tiles, not easy. This is not perfect, but an attempt.
Source Atle Mo
Number 2 in a series of 5 beautiful patterns. Can be found in colors on the submitter’s website.
Source Janos Koos
The rectangular tile this is based on can be had by selecting the rectangle in Inkscape and using shift+alt+i
Source Firkin