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 heavy hitter at 400x400px, but lovely still.
Source Breezi
A seamless background drawn in Paint.net and vectorised with Vector Magic. The starting point was a photograph of drinking straws from Pixabay.
Source Firkin
Number 4 in a series of 5 beautiful patterns. Can be found in colors on the submitter’s website.
Source Janos Koos
Prismatic Curved Diamond Pattern 3 No Background
Source GDJ
The tile this is formed from can be retrieved in Inkscape by selecting the rectangle and using shift+alt+i
Source Firkin
Prismatic Groovy Concentric Background 3
Source GDJ
Remixed from a drawing that was uploaded to Pixabay by ractapopulous
Source Firkin
I love these crisp, tiny, super subtle patterns.
Source Badhon Ebrahim
Brushed aluminum, in a bright gray version. Lovely 2X as well.
Source Andre Schouten
Seamless , tileable CC-0 texture. Created by my own, feel free to use wherever you want!
Source Linolafett
The starting point for this was drawn on the web site steamcoded.org/PolyskelionMaker.svg
Source Firkin
To get the tile this is based on, select the rectangle in Inkscape and use shift+alt+i.
Source Firkin
Horizontal and vertical lines on a light gray background.
Source Adam Anlauf
To get the tile this is formed from select the rectangle in Inkscape and use shift+alt+i.
Source Firkin
Tiny circle waves, almost like the ocean.
Source Sagive
Dark, lines, noise, tactile. You get the drift.
Source Anatoli Nicolae
A seamless pattern with wide vertical stripes colored in pale yellow.
Source V. Hartikainen
Number five from the same submitter, makes my job easy.
Source Dima Shiper
Remixed from a design found in 'History of the Virginia Company of London; with letters to and from the first Colony, never before printed', Edward Neill, 1869.
Source Firkin
A free tileable background colored in off-white (antique white) color.
Source V. Hartikainen