Here's a brown background pattern with subtle stripes. I hope you'll like the color. If not, feel free to change it using an image editor, if you know how of course. Personally, I'm using GIMP to create these backgrounds.
Source V. Hartikainen
A seamless pattern formed from miutopia mug remixes on a tablecloth.
Source Firkin
Utilising some flowers from Almeidah. To get the unit tile, select the rectangle in Inkscape and use shift-alt-i.
Source Firkin
To get the tile this is based on, select the rectangle in Inkscape and use shift+alt+i.
Source Firkin
Old China with a modern twist, take two.
Source Adam Charlts
Background formed from the iconic plastic construction bricks that gave me endless hours of fun when I was a lad.
Source Firkin
The name is totally random, but hey, it sounds good.
Source Atle Mo
As simple and subtle as it gets. But sometimes that’s just what you want.
Source Designova
Derived from an image that was uploaded to Pixabay by Darkmoon1968
Source Firkin
If you want png files of this u can download them here : viscious-speed.deviantart.com/gallery/27635117
Source Viscious-Speed
Dare I call this a «flat pattern»? Probably not.
Source Dax Kieran
Black And White Floral Pattern Background from PDP.
Source GDJ
Did some testing with Repper Pro tonight, and this gray mid-tone pattern came out.
Source Atle Mo
I guess this one is inspired by an office. A dark office.
Source Andrés Rigo.
Remixed from a JPG that was uploaded to Pixabay by theasad121
Source Firkin
A seamless pattern from a tile drawn in Paint.net and vectorised in Vector Magic
Source Firkin
By popular request, an outline version of the pentagon pattern.
Source Atle Mo
A seamless pattern from a tile made from a jpg on Pixabay. To get the tile select the rectangle in Inkscape and use shift-alt-i.
Source Firkin
To get the repeating unit, select the rectangle in Inkscape and use shift+alt+i
Source Firkin
The name alone is awesome, but so is this sweet dark pattern.
Source Federica Pelzel
Prismatic Floral Pattern 3 Variation 3 No Background
Source GDJ
Light gray grunge wall with a nice texture overlay.
Source Adam Anlauf