Super simple but very nice indeed. Gray with vertical stripes.
Source Merrin Macleod
Just the symbols of the signs of the zodiac distributed in a chequer board-like pattern
Source Firkin
A seamless pattern with wide vertical stripes colored in pale yellow.
Source V. Hartikainen
Abstract Tiled Background Extended 12
Source GDJ
Remixed from an image that was uploaded to Pixabay by KirstenStar
Source Firkin
This could be a hippy vintage wallpaper.
Source Tileable Patterns
Awesome name, great pattern. Who does not love space?
Source Nick Batchelor
A seamless texture traced from an image on opengameart.org shared by Scouser.
Source Firkin
Seamless Prismatic Quadrilateral Line Art Pattern No Background
Source GDJ
This seamless background image should look nice on websites. It has a dark blue gray texture with vertical stripes, it tiles seamlessly and, like all of the background images here, it's free. So, if you like it, take it!
Source V. Hartikainen
If you’re sick of the fancy 3D, grunge and noisy patterns, take a look at this flat 2D brick wall.
Source Listvetra
To get the tile this is based on, select the rectangle in Inkscape and use shift-alt-i.
Source Firkin
A smooth mid-tone gray, or low contrast if you will, linen pattern.
Source Jordan Pittman
A huge one at 800x600px. Made from a photo I took going home after work.
Source Atle Mo