The green fibers pattern will work very well in grayscale as well.
Source Matteo Di Capua
Zerro CC tillable texture of stones photographed and made by me. CC0
Source Sojan Janso
A seamless pattern formed from background pattern 102
Source Firkin
Zerro CC tillable texture of stones photographed and made by me. CC0
Source Sojan Janso
This background image has seamless texture that resembles a surface of gray stone.
Source V. Hartikainen
I have no idea what J Boo means by this name, but hey – it’s hot.
Source j Boo
To get the tile this is formed from select the rectangle in Inkscape and use shift+alt+i.
Source Firkin
A light gray wall or floor (you decide) of concrete.
Source Atle Mo
Prismatic Rounded Squares Grid 3 No Background
Source GDJ
CC0 and a seamless pattern from a tile drawn in Paint.net .
Source SliverKnight
Background Wall, Art Abstract, white Well & CC0 texture.
Source Ractapopulous
Some rectangles, a bit of dust and grunge, plus a hint of concrete.
Source Atle Mo
Derived from an image that was uploaded to Pixabay by Kaz
Source Firkin
I scanned a paper coffee cup. You know, in case you need it.
Source Atle Mo
To get the tile this is based on, select the rectangle in Inkscape and use shift+alt+i.
Source Firkin
Prismatic Geometric Tessellation Pattern 4 No Background
Source GDJ
I’m guessing this is related to the Sony Vaio? It’s a nice pattern no matter where it’s from.
Source Zigzain
More bright luxury. This is a bit larger than fancy deboss, and with a bit more noise.
Source Viszt Péter
This light yellow background pattern consists of an irregular pattern of spots. Here's a light background pattern with yellowish tint.
Source V. Hartikainen
New paper pattern with a slightly organic feel to it, using some thin threads.
Source Atle Mo
Snap! It’s a pattern, and it’s not grayscale! Of course you can always change the color in Photoshop.
Source Atle Mo
f you want png files of this u can download them here : viscious-speed.deviantart.com/gallery/27635117
Source Viscious-Speed
A huge one at 800x600px. Made from a photo I took going home after work.
Source Atle Mo