This could be a hippy vintage wallpaper.
Source Tileable Patterns
Seamless , tileable CC-0 texture. Created by my own, feel free to use wherever you want!
Source Linolafett
From a drawing in 'Sun Pictures of the Norfolk Broads', Ernest Suffling, 1892.
Source Firkin
Super simple but very nice indeed. Gray with vertical stripes.
Source Merrin Macleod
A seamless texture traced from an image on opengameart.org shared by Scouser.
Source Firkin
From a drawing in 'Studies for Stories', Jean Ingelow, 1864.
Source Firkin
Here's a new gray "fabric" pattern. Use it as backgrounds for websites or for other purposes.
Source V. Hartikainen
Here's a dark background pattern that contains a steel grid pattern as a texture. Use it as a website background or for other purposes. It's free!
Source V. Hartikainen
Luxurious looking pattern (for a T-shirt maybe?) with a hint of green.
Source Simon Meek
Basket Fibers, Basket Texture, Braid Background style CC0 texture.
Source 1A-Photoshop
A light gray wall or floor (you decide) of concrete.
Source Atle Mo
A seamless texture traced from an image on opengameart.org shared by Scouser.
Source Firkin
Based on several public domain drawings on Wikimedia Commons. This was formed from a rectangular tile. The tile can be accessed in Inkscape by selecting the rectangle and using shift-alt-i.
Source Firkin
Some rectangles, a bit of dust and grunge, plus a hint of concrete.
Source Atle Mo
From a drawing in 'Royal Ramsgate', James Simson, 1897.
Source Firkin
Prismatic Groovy Concentric Background 4
Source GDJ
Remixed from a drawing in 'Chambéry à la fin du XIVe siècle', Timoleon Chapperon, 1863.
Source Firkin
A seamless pattern the starting point for which was a 'rainbow twist' texture in Paint.net.
Source Firkin
To get the tile this is based on, select the rectangle in Inkscape and use shift+alt+i.
Source Firkin
The tile this is based on can be retrieved by selecting the rectangle in Inkscape and using shift+alt+i.
Source Firkin
Same classic 45-degree pattern, dark version.
Source Luke McDonald
Not a pattern for fabrics, but one produced from a jpg of a stack of fabric items that was posted on Pixabay. The tile that this is based on can be had by selecting the rectangle in Inkscape and using shift+alt+i.
Source Firkin
A seamless paper background colored in pale yellow.
Source V. Hartikainen
Tiny, tiny 3D cubes. Reminds me of the good old pattern from k10k.
Source Etienne Rallion