Detailed but still subtle and quite original. Lovely gray shades.
Source Kim Ruddock
Here's a brown background pattern with subtle stripes. I hope you'll like the color. If not, feel free to change it using an image editor, if you know how of course. Personally, I'm using GIMP to create these backgrounds.
Source V. Hartikainen
Prismatic Floral Pattern 3 Variation 3 No Background
Source GDJ
Dark squares with some virus-looking dots in the grid.
Source Hugo Loning
From a drawing in 'In an Enchanted Island', William Mallock, 1892.
Source Firkin
Tiny little fibers making a soft and sweet look.
Source Badhon Ebrahim
Prismatic Basic Pattern 2 No Background
Source GDJ
Remixed from a JPG that was uploaded to Pixabay by susanlu4esm
Source Firkin
The base gradient edited so now more details are rendered.
Source Lazur URH
This one takes you back to math class. Classic mathematic board underlay.
Source Josh Green
To get the tile this is based on, select the rectangle in Inkscape and use shift-alt-i.
Source Firkin
A free seamless background with pink spots.
Source V. Hartikainen
A light brushed aluminum pattern for your pleasure.
Source Tim Ward
Pixel by pixel, sharp and clean. Very light pattern with clear lines.
Source M.Ashok
Could remind you a bit of those squares in Super Mario Bros, yeh?
Source Jeff Wall
Recreated from a pattern found in 'Az Osztrák-Magyar Monarchia irásban és képben', 1882. To get the tile this is based on select the rectangle in Inkscape and use shift+alt+i.
Source Firkin
Zerro CC tillable texture of stones photographed and made by me. CC0
Source Sojan Janso
From a drawing in 'Chambéry à la fin du XIVe siècle', Timoleon Chapperon, 1863.
Source Firkin
Vector version of a png that was uploaded to Pixabay by pencilparker
Source Firkin