A dark metal plate with an embossed grid pattern and a bit of rust. Here's a dark metal plate texture for use as a tiled background on web pages.
Source V. Hartikainen
The unit cell for this seamless pattern can be had in Inkscape by selecting the rectangle and using shift+alt+i.
Source Firkin
Derived from a drawing in 'The Murmur of the Shells', Samuel Cowen, 1879.
Source Firkin
Derived from elements found in a floral ornament drawing on Pixabay.
Source Firkin
From a drawing in 'Sun Pictures of the Norfolk Broads', Ernest Suffling, 1892.
Source Firkin
A seamless texture of worn out "cardboard".
Source V. Hartikainen
Psychedelic Geometric Background No Black
Source GDJ
Prismatic Rounded Squares Grid 3 No Background
Source GDJ
Like the name says, light and gray, with some small dots and circles.
Source Brenda Lay
Prismatic Triangular Seamless Pattern III With Background
Source GDJ
Floral patterns will never go out of style, so enjoy this one.
Source Lasma
Remixed from a drawing in 'The Canadian horticulturist', 1892
Source Firkin
Looks a bit like concrete with subtle specks spread around the pattern.
Source Mladjan Antic
A seamless pale yellow paper background with a pattern of animal tracks.
Source V. Hartikainen
The Grid. A digital frontier. I tried to picture clusters of information as they traveled through the computer.
Source Haris Šumić
An alternative colour scheme for the original seamless texture formed from an image on Pixabay.
Source Firkin
If you want png files of this u can download them here : viscious-speed.deviantart.com/gallery/27635117
Source Viscious-Speed
There are quite a few grid patterns, but this one is a super tiny grid with some dust for good measure.
Source Dominik Kiss
Prismatic Abstract Line Art Pattern Background
Source GDJ