Seamless Light Background Texture.
Source V. Hartikainen
Used correctly, this could be nice. Used in a bad way, all hell will break loose.
Source Atle Mo
Bright gray tones with a hint of some metal surface.
Source Hendrik Lammers
Inspired by a drawing in 'Kulturgeschichte', Freidrich Hellwald, 1896.
Source Firkin
A car pattern?! Can it be subtle? I say yes!
Source Radosław Rzepecki
Prismatic Snowflakes Pattern No Background
Source GDJ
Classic vertical lines, in all its subtlety.
Source Cody L
Zero CC tileable hard cover green book, scanned and made by me. CC0
Source Sojan Janso
You could get a bit dizzy from this one, but it might come in handy.
Source Dertig Media
Honestly, who does not like a little pipe and mustache?
Source Luca Errico
Subtle scratches on a light gray background.
Source Andrey Ovcharov
Seamless pattern the tile for which can be had by using shift-alt-I on the selected rectangle in Inkscape.
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
High detail stone wall with minor cracks and specks.
Source Projecteightyfive
Formed by distorting the inside front cover of 'Diversæ insectarum volatilium : icones ad vivum accuratissmè depictæ per celeberrimum pictorem', Jacob Hoefnagel, 1630.
Source Firkin
A seamless pattern from a tile drawn in Paint.net and vectorised in Vector Magic
Source Firkin
Might not be super subtle, but quite original in its form.
Source Alex Smith
CC0 and a seamless pattern from a tile drawn in Paint.net .
Source SliverKnight
A seamless pattern of dark bricks. Maybe it's not very realistic, but it looks good in my opinion.
Source V. Hartikainen
Made by distorting a simple pattern using the 'sin waves' plugin for Paint.net and vectorising in Vector Magic
Source Firkin
To get the tile this is based on, select the rectangle in Inkscape and use shift+alt+i.
Source Firkin
Never out of fashion and so much hotter than the 45º everyone knows, here is a sweet 60º line pattern.
Source Atle Mo