A repeating gloomy background image. This one consists of a pattern of black chains layered on top of a dark textured background.
Source V. Hartikainen
A very dark asfalt pattern based off of a photo taken with my iPhone.
Source Atle Mo
This one is so simple, yet so good. And you know it. Has to be in the collection.
Source Gluszczenko
Nothing like a clean set of bed sheets, huh?
Source Badhon Ebrahim
Seamless pattern the tile for which can be had by using shift-alt-I on the selected rectangle in Inkscape.
Source Firkin
Remixed from a drawing in 'Sun Pictures of the Norfolk Broads', Ernest Suffling, 1892.
Source Firkin
A monochrome pattern from a tile that can be had by selecting the rectangle in Inkscaope and using shift+alt+i
Source Firkin
Super detailed 16×16 tile that forms a beautiful pattern of straws.
Source Pavel
Lovely light gray floral motif with some subtle shades.
Source GraphicsWall
ZeroCC tileable moss texture, photographed and made by me. CC0
Source Sojan Janso
From a drawing in 'A Life Interest', Mrs Alexander, 1888.
Source Firkin
Bright gray tones with a hint of some metal surface.
Source Hendrik Lammers
Abstract Ellipses Background Grayscale
Source GDJ
The image depicts a Japanese Edo pattern called "kanoko or 鹿の子" meaning "fawn" which has a fur with small white spots.
Source Yamachem
Prismatic Groovy Concentric Background 4 No Black
Source GDJ
A playful triangle pattern with different shades of gray.
Source Dimitrie Hoekstra
Not strictly seamless in that opposite edges are not identical. But they do marry up to make an interesting pattern
Source Firkin
Cubes as far as your eyes can see. You know, because they tile.
Source Jan Meeus
Nice and simple crossed lines in dark gray tones.
Source Stefan Aleksić
Love the style on this one, very fresh. Diagonal diamond pattern. Get it?
Source INS
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
Number 4 in a series of 5 beautiful patterns. Can be found in colors on the submitter’s website.
Source Janos Koos