A pattern drawn in Paint.net and vectorized in Inkscape.
Source Firkin
Looks like a technical drawing board: small squares forming a nice grid.
Source We Are Pixel8
This is lovely, just the right amount of subtle noise, lines and textures.
Source Richard Tabor
Sometimes simple really is what you need, and this could fit you well.
Source Factorio.us Collective
Prismatic Snowflakes Pattern 2 No Background
Source GDJ
Could be paper, could be a Polaroid frame – up to you!
Source Chaos
From a drawing in 'Line and form', Walter Crane, 1914.
Source Firkin
Prismatic Groovy Concentric Background 5 No Black
Source GDJ
A seamless pattern recreated from an image on Pixabay. It is reminiscent of parquet flooring and is formed from a square tile, which can be recovered in Inkscape by selecting the ungrouped rectangle and using shift-alt-I together.
Source Firkin
Prismatic Hexagonalism Pattern No Background
Source GDJ
A seamless pattern formed from background pattern 102
Source Firkin
Actually remixed from a pattern on Pixabay. But then noticed a very similar one on Openclipart.org uploaded by btj51q2.
Source Firkin
More carbon fiber for your collections. This time in white or semi-dark gray.
Source Badhon Ebrahim
From a design found in 'History of the Virginia Company of London; with letters to and from the first Colony, never before printed', Edward Neill, 1869.
Source Firkin
Seamless pattern inspired by a drawing on Pixabay. To get the tile this is formed from, select the rectangle in Inkscape and use shift-alt-i.
Source Firkin
From a drawing in 'Uit de geschiedenis der Heilige Stede te Amsterdam', Yohannes Sterck, 1898.
Source Firkin
The tile can be had by selecting the rectangle in Inkscape and using shift+alt+i. Remixed from a drawing in 'Flowers of Song', Frederick Weatherly, 1895.
Source Firkin
Could remind you a bit of those squares in Super Mario Bros, yeh?
Source Jeff Wall
Retro Circles Background 7 No Black
Source GDJ
There are many carbon patterns, but this one is tiny.
Source Designova
From a drawing in 'Heroes of North African Discovery', Nancy Meugens, 1894.
Source Firkin