You don’t see many mid-tone patterns here, but this one is nice.
Source Joel Klein
Remixed from a drawing in 'Jezebel's Daughter', Wilkie Collins 1880
Source Firkin
Prismatic Groovy Concentric Background 5 No Black
Source GDJ
Remixed from a vector adapted from a jpg on Pixabay. The tile this is constructed from can be had by selecting the rectangle in Inkscape and using shift-alt-i.
Source Firkin
From a drawing in 'Sun Pictures of the Norfolk Broads', Ernest Suffling, 1892.
Source Firkin
It’s okay to be square! A nice light gray pattern with random squares.
Source Waseem Dahman
Remixed from a JPG that was uploaded to Pixabay by susanlu4esm
Source Firkin
Made by distorting a simple pattern using the 'sin waves' plugin for Paint.net and vectorising in Vector Magic
Source Firkin
Wild Oliva or Oliva Wilde? Darker than the others, sort of a medium dark pattern.
Source Badhon Ebrahim
Colorful Floral Background 3 No Black
Source GDJ
Prismatic Isometric Cube Extra Pattern No Background
Source GDJ
Remixed from a design seen on Pixabay. The basic tile can be had by selecting the rectangle in Inkscape and using shift+alt+i
Source Firkin
A frame using leaves from an image that was uploaded to Pixabay by mayapujiati
Source Firkin
Remixed from a drawing in 'Line and form', Walter Crane, 1914.
Source Firkin
Remixed from an image that was uploaded to Pixabay by Pixeline
Source Firkin
Zerro CC tillable texture of stones photographed and made by me. CC0
Source Sojan Janso
CC0 and a seamless pattern from a tile drawn in Paint.net .
Source SliverKnight
A free tileable background colored in off-white (antique white) color.
Source V. Hartikainen