Tiny circle waves, almost like the ocean.
Source Sagive
From a tile that can be had by selecting the rectangle in Inkscape and using shift+alt+i.
Source Firkin
A dark gray, sandy pattern with small light dots, and some angled strokes.
Source Atle Mo
Hexagonal dark 3D pattern. What more can you ask for?
Source Norbert Levajsics
Prismatic Groovy Concentric Background 2
Source GDJ
Formed from decorative divider 184 in paint.net. Vectorised with Vector Magic.
Source Firkin
I guess this is inspired by the city of Ravenna in Italy and its stone walls.
Source Sentel
Kaleidoscope Prismatic Abstract No Background
Source GDJ
Remixed from a drawing in 'Maidenhood; or, the Verge of the Stream', Laura Jewry, 1876.
Source Firkin
Nice and simple crossed lines in dark gray tones.
Source Stefan Aleksić
A cute x, if you need that sort of thing.
Source Juan Scrocchi
Dark, square, clean and tidy. What more can you ask for?
Source Jaromír Kavan
It almost looks a bit blurry, but then again, so are fishes.
Source Petr Šulc
Found on the ground in french cafe in kunming, Yunnan, china
Source Rejon
After 1 comes 2, same but different. You get the idea.
Source Hendrik Lammers
A seamless stone-like background for blogs or any other type of websites.
Source V. Hartikainen
Sharp diamond pattern. A small 24x18px tile.
Source Tom Neal
From a drawing in 'Az Osztrák-Magyar Monarchia irásban és képben', 1885.
Source Firkin
Prismatic Groovy Concentric Background
Source GDJ
From a drawing in 'At home', J. Sowerby, J. Crane and T. Frederick, 1881.
Source Firkin
The name tells you it has curves. Oh yes, it does!
Source Peter Chon
A classic dark tile for a bit of vintage darkness.
Source Listvetra
Alternative colour scheme. 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