This one takes you back to math class. Classic mathematic board underlay.
Source Josh Green
Formed by heavily distorting part of a an image of a fish uploaded to Pixabay by GLady
Source Firkin
You may use it as is, or modify it as you like.
Source V. Hartikainen
Inspired by a JPG that was uploaded to Pixabay by kokon_art
Source Firkin
Seamless pattern formed from a tile that can be had by selecting the rectangle in Inkscape and using shift-alt-i.
Source Firkin
A free seamless background with pink spots.
Source V. Hartikainen
Remixed from a drawing in 'Sun Pictures of the Norfolk Broads', Ernest Suffling, 1892.
Source Firkin
A light gray fabric pattern with faded vertical stripes.
Source V. Hartikainen
Abstract Arbitrary Geometric Background derived from an image on Pixabay.
Source GDJ
From a drawing in 'Les Chroniqueurs de l'Histoire de France depuis les origines jusqu'au XVIe siècle', Henriette Witt, 1884.
Source Firkin
This was formed by distorting an image of a background on Pixabay.
Source Firkin
This white background pattern has a seamless grunge style texture. Here's a white grunge style background pattern. Use it as a tiled background image on web sites or for other purposes.
Source V. Hartikainen
Fake or not, it’s quite luxurious.
Source Factorio.us Collective
The unit cell for this seamless pattern can be had in Inkscape by selecting the rectangle and using shift+alt+i.
Source Firkin
This background pattern contains worn out colorful stripes as a texture.
Source V. Hartikainen
Abstract Tiled Background Extended 8
Source GDJ
Plywood Web Background background image for use in web design.
Source V. Hartikainen
Seamless pattern formed from a tile that can be extracted by selecting the rectangle in Inkscape and using shift-alt-i.
Source Firkin
Sounds French. Some 3D square diagonals, that’s all you need to know.
Source Graphiste
To get the tile this is based on, select the rectangle in Inkscape and use shift-alt-i.
Source Firkin
The classic notebook paper with horizontal stripes.
Source Are Sundnes
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
A fun-looking elastoplast/band-aid pattern. A hint of orange tone in this one.
Source Josh Green