Looks like a technical drawing board: small squares forming a nice grid.
Source We Are Pixel8
A slightly more textured pattern, medium gray. A bit like a potato sack?
Source Bilal Ketab
Colorful Floral Background No Black
Source GDJ
Prismatic Hypnotic Pattern 2 No Background
Source GDJ
Prismatic Abstract Geometric Background 5
Source GDJ
A seamless pattern with a unit cell drawn as a bitmap in Paint.net and vectorized in Vector Magic.
Source Firkin
Derived from elements found in a floral ornament drawing on Pixabay.
Source Firkin
Bumps, highlight and shadows – all good things.
Source Badhon Ebrahim
Floral patterns might not be the hottest thing right now, but you never know when you need it!
Source Lauren
A seamless chequerboard pattern formed from a tile that can be had in Inkscape by selecting the rectangle and using shift+alt+i. Alternative colour scheme.
Source Firkin
Prismatic Abstract Line Art Pattern Background 2
Source GDJ
Remixed from a drawing in 'Jezebel's Daughter', Wilkie Collins 1880
Source Firkin
From a drawing in 'At home', J. Sowerby, J. Crane and T. Frederick, 1881.
Source Firkin
Little x’es, noise and all the stuff you like. Dark like a Monday, with a hint of blue.
Source Tom McArdle
Zero CC tillable hard cover red book with X shape marks. Scanned and made by me.
Source Sojan Janso
Not strictly seamless in that opposite edges are not identical. But they do marry up to make an interesting pattern
Source Firkin
The image depicts the Japanese Edo pattern called "seigaiha" or "青海波" meaning "blue -sea- wave".I hope it's suitable for the summer season.
Source Yamachem
The tile this is based on can be retrieved by selecting the rectangle in Inkscape and using shift+alt+i.
Source Firkin
Zerro CC tillable texture of stones photographed and made by me. CC0
Source Sojan Janso
A slightly more textured pattern, medium gray. A bit like a potato sack?
Source Bilal Ketab
Honestly, who does not like a little pipe and mustache?
Source Luca Errico
Seamless , tileable CC-0 texture. Created by my own, feel free to use wherever you want!
Source Linolafett
You know I love paper patterns. Here is one from Stephen. Say thank you!
Source Stephen Gilbert
From a drawing in 'Art Embroidery', M.S. Lockwood and E. Glaister, 1878.
Source Firkin
Square design drawn in Paint.net and vectorized in Vector Magic.
Source Firkin