Might not be super subtle, but quite original in its form.
Source Alex Smith
From a drawing in 'Art Embroidery', M.S. Lockwood and E. Glaister, 1878.
Source Firkin
The image depicts a seamless pattern of a fishnet with a plenty of fish.It may be a lucky charm for fishermen.
Source Yamachem
A seamless pattern from a tile drawn in Paint.net and vectorised in Vector Magic
Source Firkin
Black paper texture, based on two different images.
Source Atle Mo
Based from Design Kindle
This one takes you back to math class. Classic mathematic board underlay.
Source Josh Green
A monochrome pattern from a tile that can be had by selecting the rectangle in Inkscaope and using shift+alt+i
Source Firkin
A bit like smudged paint or some sort of steel, here is scribble light.
Source Tegan Male
Zerro CC tillable texture of stones photographed and made by me. CC0
Source Sojan Janso
Three shades of gray makes this pattern look like a small carbon fiber surface. Great readability even for small fonts.
Source Atle Mo
To get the tile this is based on, select the rectangle in Inkscape and use shift+alt+i.
Source Firkin
Classic vertical lines, in all its subtlety.
Source Cody L
Background Wall, Art Abstract, Watercolor Vintage style CC0 texture.
Source Ractapopulous
Prismatic Curved Diamond Pattern 6 No Background
Source GDJ
A huge one at 800x600px. Made from a photo I took going home after work.
Source Atle Mo
To get the tile this is based on, select the rectangle in Inkscape and use shift+alt+i.
Source Firkin
Got some felt in my mailbox today, so I scanned it for you to use.
Source Atle Mo
The name alone is awesome, but so is this sweet dark pattern.
Source Federica Pelzel
Some rectangles, a bit of dust and grunge, plus a hint of concrete.
Source Atle Mo
Geometric lines are always hot, and this pattern is no exception.
Source Listvetra
Inspired by the B&O Play, I had to make this pattern.
Source Atle Mo
Textured Red Brown Plastic, Free Background Pattern. Although there's already enough plastic in our lives, let's bring it to the web too.)
Source V. Hartikainen
If you want png files of this u can download them here : viscious-speed.deviantart.com/gallery/27635117
Source Viscious-Speed
Heavy depth and shadows here, but might work well on some mobile apps.
Source Damian Rivas
A seamless web texture of "green stone".
Source V. Hartikainen
A seamless pattern formed from cross 4. To get the original tile select the rectangle in Inkscape and use shift-alt-i.
Source Firkin