Looks like a technical drawing board: small squares forming a nice grid.
Source We Are Pixel8
From a drawing in 'A Life Interest', Mrs Alexander, 1888.
Source Firkin
Prismatic Polka Dots 3 No Background
Source GDJ
This is a remix of "geometrical pattern 01".
Source Yamachem
Actually remixed from a pattern on Pixabay. But then noticed a very similar one on Openclipart.org uploaded by btj51q2.
Source Firkin
I know there is one here already, but this is sexy!
Source Gjermund Gustavsen
A seamless pattern drawn originally in Paint.net by distorting a slice of background pattern 116 and copying the resulting triangle numerous times.
Source Firkin
Paper pattern with small dust particles and 45-degree strokes.
Source Atle Mo
Remixed from a raster on Pixabay, that was uploaded by ArtsyBee.
Source Firkin
Imagine you zoomed in 1000X on some fabric. But then it turned out to be a skeleton!
Source Angelica
If you like it a bit trippy, this wave pattern might be for you.
Source Ian Soper
A seamless texture traced from an image on opengameart.org shared by Scouser.
Source Firkin
Seamless Prismatic Pythagorean Line Art Pattern No Background. A seamless pattern that includes the original tile (go to Objects / Pattern / Pattern To Objects in Inkscape's menu to extract it).
Source GDJ
A very dark spotted twinkle pattern for your twinkle needs.
Source Badhon Ebrahim
The tile this is based on can be had by selecting the rectangle in Inkscape and using shift+alt+i
Source Firkin
A seamless chequerboard pattern formed from a tile that can be had in Inkscape by selecting the rectangle and using shift+alt+i.
Source Firkin
After 1 comes 2, same but different. You get the idea.
Source Hendrik Lammers
Clover with background for St. Patrick's Day. Add to a card with a doily, ribbon, a leprechaun or other embellishments.
Source BAJ
This one could be the shirt of a golf player. Angled lines in different thicknesses.
Source Olivier Pineda