Seamless pattern the tile for which can be had by using shift-alt-I on the selected rectangle in Inkscape.
Source Firkin
Sharp pixel pattern looking like some sort of fabric.
Source Dmitry
A seamless pattern formed from a square tile. To get the 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
This reminds me of Game Cube. A nice light 3D cube pattern.
Source Sander Ottens
Used the 6th circle pattern designed by Viscious-Speed to create a print that can be used for card making or scrapbooking. Save as a PDF file for the best printing option.
Source Lovinglf
Remixed from a design seen on Pixabay. The basic tile can be had by selecting the rectangle in Inkscape and using shift+alt+i
Source Firkin
Background Wall, Art Abstract, Blue Well & CC0 texture.
Source Ractapopulous
A free tileable background colored in off-white (antique white) color.
Source V. Hartikainen
Prismatic Polka Dots Mark II 3 No Background
Source GDJ
Recreated from a pattern found in 'Az Osztrák-Magyar Monarchia irásban és képben', 1882. To get the tile this is based on select the rectangle in Inkscape and use shift+alt+i.
Source Firkin
Lovely pattern with some good-looking non-random noise lines.
Source Zucx
CC0 and a seamless pattern from a tile drawn in Paint.net .
Source SliverKnight
Could be paper, could be a Polaroid frame – up to you!
Source Chaos
Sometimes simple really is what you need, and this could fit you well.
Source Factorio.us Collective
And some more testing, this time with Seamless Studio. It’s Robots FFS!
Source Seamless Studio
Zerro CC tillable texture of stones photographed and made by me. CC0
Source Sojan Janso
Super subtle indeed, a medium gray pattern with tiny dots in a grid.
Source Designova
The image depicts a seamless pattern made using a bird's face.
Source Yamachem
Remix from a drawing in 'Ostatnie chwile powstania styczniowego', Zygmunt Sulima, 1887.
Source Firkin