A mid-tone gray pattern with some cement looking texture.
Source Hendrik Lammers
It almost looks a bit blurry, but then again, so are fishes.
Source Petr Šulc
Green Background Pattern
Source V. Hartikainen
To get the tile this is based on select the rectangle in Inkscape and use shift-alt-i.
Source Firkin
Prismatic Hypnotic Pattern 2 No Background
Source GDJ
You don’t see many mid-tone patterns here, but this one is nice.
Source Joel Klein
This ladies and gentlemen, is texturetastic! Love it.
Source Adam Pickering
Looks like a technical drawing board: small squares forming a nice grid.
Source We Are Pixel8
CC0 and a seamless pattern from a tile drawn in Paint.net .
Source SliverKnight
There are quite a few grid patterns, but this one is a super tiny grid with some dust for good measure.
Source Dominik Kiss
A background pattern with blue on white vertical stripes.
Source V. Hartikainen
A seamless pattern from a tile drawn in Paint.net and vectorised in Vector Magic
Source Firkin
Remixed from a drawing in 'Line and form', Walter Crane, 1914.
Source Firkin
To get the tile this is based on select the rectangle in Inkscape and use shift+alt+i.
Source Firkin
Super simple but very nice indeed. Gray with vertical stripes.
Source Merrin Macleod
Abstract Tiled Background Extended 10
Source GDJ
Black brick wall pattern. Brick your site up!
Source Alex Parker
Colorful Floral Background 3 No Black
Source GDJ
An interesting dark spotted pattern at an angle.
Source Hendrik Lammers