Here's a repeatable texture that resembles a light green concrete wall or something similar.
Source V. Hartikainen
A background tile for web with abstract repeating texture of dark "stone wall".
Source V. Hartikainen
A yellow tiled background... Blurriness, bokeh effect and rectangles pattern in one mix.
Source V. Hartikainen
The green fibers pattern will work very well in grayscale as well.
Source Matteo Di Capua
A seamless texture traced from an image on opengameart.org shared by Scouser.
Source Firkin
I skipped number 3, because it wasn’t all that great. Sorry.
Source Dima Shiper
Prismatic Snowflakes Pattern 2 No Background
Source GDJ
Sweet and subtle white plaster with hints of noise and grunge.
Source Phil Maurer
Zero CC asphalt, pavement, texture, photographed and made by me. CC0 WARNING I FOUND A SEAM ON THIS TEXTURE
Source Sojan Janso
The tile this is based on can be retrieved by selecting the rectangle in Inkscape and using shift+alt+i.
Source Firkin
A mid-tone gray pattern with some cement looking texture.
Source Hendrik Lammers
The original enhanced with one of Inkscapes's filters.
Source Firkin
The name alone is awesome, but so is this sweet dark pattern.
Source Federica Pelzel
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
Super dark, crisp and detailed. And a Kill Bill reference.
Source Badhon Ebrahim
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
Number five from the same submitter, makes my job easy.
Source Dima Shiper
Prismatic Abstract Background Design No Black
Source GDJ
Prismatic Abstract Geometric Background 4
Source GDJ
Sounds French. Some 3D square diagonals, that’s all you need to know.
Source Graphiste
A nice and simple gray stucco material. Great on its own, or as a base for a new pattern.
Source Bartosz Kaszubowski