A comeback for you: the popular Escheresque, now in black.
Source Patten
A heavy dark gray base, some subtle noise and a 45-degree grid makes this look like a pattern with a tactile feel to it.
Source Atle Mo
A grid of squares with green colours. Since the colours are randomly distributed it is automatically seamless.
Source Firkin
Washi (和紙?) is a type of paper made in Japan. Here’s the pattern for you!
Source Carolynne
This is the remix of "blue wave-seigaiha".The image depicts a seamless pattern of the front upper part of Japanese five yen coin which is used currently.This design represents a rice with ripe golden ears.
Source Yamachem
Simple gray checkered lines, in light tones.
Source Radosław Rzepecki
All good things come in threes, so I give you the third in my little concrete wall series.
Source Atle Mo
Here's a camo print with more tan and less green, such as might be used in a desert scenario. This is tileable, so it can be used as a wallpaper or background.
Source Eady
This is the remix of "polka dot seamless pattern".The image depicts polka dot seamless pattern.
Source Yamachem
Hexagonal dark 3D pattern. What more can you ask for?
Source Norbert Levajsics
Some rectangles, a bit of dust and grunge, plus a hint of concrete.
Source Atle Mo
The unit cell for this seamless pattern can be had in Inkscape by selecting the rectangle and using shift+alt+i.
Source Firkin
Prismatic Groovy Concentric Background 5 No Black
Source GDJ
Colour version that is close to the original drawing uploaded to Pixabay by pencilparker.
Source Firkin
This is a remix of "blue wave-seigaiha".I hope this subtle color version of Seigaiha would be suitable for background .
Source Yamachem
Light gray grunge wall with a nice texture overlay.
Source Adam Anlauf
Super detailed 16×16 tile that forms a beautiful pattern of straws.
Source Pavel
This was submitted in a beige color, hence the name. Now it’s a gray paper pattern.
Source Konstantin Ivanov
Geometric lines are always hot, and this pattern is no exception.
Source Listvetra
Not a pattern for fabrics, but one produced from a jpg of a stack of fabric items that was posted on Pixabay. The tile that this is based on can be had by selecting the rectangle in Inkscape and using shift+alt+i.
Source Firkin
The square tile this is based on can be had by selecting the rectangle in Inkscape and using shift+alt+i
Source Firkin
Sweet and subtle white plaster with hints of noise and grunge.
Source Phil Maurer
Imagine you zoomed in 1000X on some fabric. But then it turned out to be a skeleton!
Source Angelica