It almost looks a bit blurry, but then again, so are fishes.
Source Petr Šulc
A seamless pattern the unit cell for which can be had by selecting the rectangle in Inkscape and using shift+alt+i.
Source Firkin
Retro Circles Background 4 No Black
Source GDJ
Derived from elements found in a floral ornament drawing on Pixabay.
Source Firkin
Zero CC tileable hard cover green book, scanned and made by me. CC0
Source Sojan Janso
Sharp pixel pattern, just like the good old days.
Source Paridhi
Remixed from a drawing in 'Some account of the Worshipful Company of Ironmongers', John Nicholl, 1866.
Source Firkin
Sharp but soft triangles in light shades of gray.
Source Pixeden
Inspired by a pattern seen on a public domain image of a very old tile. To get the unit cell, select the rectangle in Inkscape and use shift+alt+i.
Source Firkin
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
The first pattern on here using opacity. Try it on a site with a colored background, or even using mixed colors.
Source Nathan Spady
The image depicts an edo-era pattern called "same-komon" or "鮫小紋"which looks like a shark skin.The "same" in Japanese means shark in English.
Source Yamachem
Seamless pattern the basic tile for which can be had by selecting the rectangle in Inkscape and using shift+alt+i.
Source Firkin
Just the symbols of the signs of the zodiac distributed in a chequer board-like pattern
Source Firkin
This is a remix of "geometrical pattern 01".
Source Yamachem
Prismatic Basic Pattern 2 No Background
Source GDJ
This was formed by distorting an image of a background on Pixabay.
Source Firkin
It looks very nice I think.
Source V. Hartikainen
A seamless pattern recreated from an image on Pixabay. It is reminiscent of parquet flooring and is formed from a square tile, which can be recovered in Inkscape by selecting the ungrouped rectangle and using shift-alt-I together.
Source Firkin
Looks like an old rug or a computer chip.
Source Patutin Sergey
Prismatic Snowflakes Pattern 2 No Background
Source GDJ
A seamless background colored in pale orange. It has a paper like texture with diagonal grid pattern.
Source V. Hartikainen
Remixed from a drawing in 'Chambéry à la fin du XIVe siècle', Timoleon Chapperon, 1863.
Source Firkin
Inspired by a design found in 'Konstantinápolyi emlékeim', Miklos Chriszto, 1893.
Source Firkin
Remixed from a drawing in 'A Girl in Ten Thousand', Elizabeth Meade, 1896.
Source Firkin
Prismatic Groovy Concentric Background 5 No Black
Source GDJ
Prismatic Geometric Tessellation Pattern 2 No Background
Source GDJ