The tile this is based on can be had by selecting the rectangle in Inkscape and using shift+alt+i
Source Firkin
A seamless pattern from a tile drawn in Paint.net and vectorised in Vector Magic
Source Firkin
This ladies and gentlemen, is texturetastic! Love it.
Source Adam Pickering
Zero CC tileable Crackled Cement (streaks) texture, photographed and made by me. CC0
Source Sojan Janso
Prismatic Abstract Geometric Background 2
Source GDJ
Got some felt in my mailbox today, so I scanned it for you to use.
Source Atle Mo
Prismatic Abstract Background Design
Source GDJ
A free black metallic background pattern. Here's a new pattern I made that looks metallic.
Source V. Hartikainen
Zero CC tileable hard cover green book, scanned and made by me. CC0
Source Sojan Janso
A seamless pattern of dark bricks. Maybe it's not very realistic, but it looks good in my opinion.
Source V. Hartikainen
Bit of a strange name on this one, but still nice. Tiny gray square things.
Source Carlos Valdez
emixed from a JPG that was uploaded to Pixabay by Kyotime
Source Firkin
The first pattern on here using opacity. Try it on a site with a colored background, or even using mixed colors.
Source Nathan Spady
A seamless pattern from a tile drawn in Paint.net and vectorised in Vector Magic
Source Firkin
A heavy hitter at 400x400px, but lovely still.
Source Breezi
Zerro CC tillable texture of stones photographed and made by me. CC0
Source Sojan Janso
A seamless texture traced from an image on opengameart.org shared by Scouser.
Source Firkin
It was called Navy Blue, but I made it dark. You know, the way I like it.
Source Ethan Hamilton
A car pattern?! Can it be subtle? I say yes!
Source Radosław Rzepecki
A seamless texture traced from an image on opengameart.org shared by Scouser.
Source Firkin