A seamless background pattern with impressed gray dots.
Source V. Hartikainen
Sometimes simple really is what you need, and this could fit you well.
Source Factorio.us Collective
Simple combination of stripy squares with their negatively coloured counterparts
Source Firkin
A seamless tessellation pattern. To get the tile this is formed from, select the pattern in Inkscape and use shift+alt+i.
Source Firkin
Inspired by a pattern found in 'A General History of Hampshire, or the County of Southampton, including the Isle of Wight', Bernard Woodwood, 1861
Source Firkin
Luxury pattern, looking like it came right out of Paris.
Source Daniel Beaton
This pattern comes in orange, and it looks as if it is "made of glass".
Source V. Hartikainen
This is the remix of an Openclipart clipart called "Maze" uploaded by "any_ono_mous".Thanks.This is a seamless pattern of a maze.
Source Yamachem
Dark Tile-able Grunge Texture. I think this texture can be classified as grunge. It's free and seamless, as always.
Source V. Hartikainen
This could be a hippy vintage wallpaper.
Source Tileable Patterns
Horizontal and vertical lines on a light gray background.
Source Adam Anlauf
Prismatic Abstract Geometric Background 2 No Black
Source GDJ
One more in the line of patterns inspired by Japanese/Asian styles. Smooth.
Source Kim Ruddock
Prismatic Geometric Pattern Background 2
Source GDJ
Simple gray checkered lines, in light tones.
Source Radosław Rzepecki
Abstract Stars Geometric Pattern Prismatic No Background
Source GDJ
The tile this is based on can be had by selecting the rectangle in Inkscape and using shift+alt+i
Source Firkin
A seamless pattern of "sewn stripes" colored in light gray.
Source V. Hartikainen
A free seamless background texture of "timber wall" (colored in dark brown).
Source V. Hartikainen
A repeating background of beige paper with vintage look. Repeats to infinity, as usual.
Source V. Hartikainen
Seamless pattern formed from a tile that can be had by selecting the rectangle in Inkscape and using shift+alt+i
Source Firkin
From a drawing in 'Worsborough; its historical associations and rural attractions', Joseph Wilkinson, 1879.
Source Firkin
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
Dark and hard, just the way we like it. Embossed triangles makes a nice pattern.
Source Ivan Ginev