Seamless pattern the tile for which can be had by using shift-alt-I on the selected rectangle in Inkscape.
Source Firkin
A pattern derived from repeating unit cells each derived from part of a fractal rendering in paint.net.
Source Firkin
A grid of squares with green colours. Since the colours are randomly distributed it is automatically seamless.
Source Firkin
A pattern formed from a photograph of a 16th century ceramic tile.
Source Firkin
Otis Ray Redding was an American soul singer-songwriter, record producer, arranger, and talent scout. So you know.
Source Thomas Myrman
Produced using the clouds, flames and glass blocks plug-ins in Paint.net and the resulting .PNG vectorised with Vector Magic.
Source Firkin
A repeating background with seamless texture of stone. There haven't been any stone-like backgrounds for a while, so I have decided to create one more. The rest can be found in the appropriate category.
Source V. Hartikainen
A seamless pattern formed from a tile made from page ornament 22. To get the tile, select the rectangle in Inkscape and use shift+alt+i.
Source Firkin
Formed by distorting the inside front cover of 'Diversæ insectarum volatilium : icones ad vivum accuratissmè depictæ per celeberrimum pictorem', Jacob Hoefnagel, 1630.
Source Firkin
A smooth mid-tone gray, or low contrast if you will, linen pattern.
Source Jordan Pittman
ZeroCC tileable stone texture, edited from pixabay. CC0
Source Sojan Janso
Your eyes can trip a bit from looking at this – use it wisely.
Source Michal Chovanec
Prismatic Curved Diamond Pattern 6 No Background
Source GDJ
With a name this awesome, how can I go wrong?
Source Nikolay Boltachev
Some rectangles, a bit of dust and grunge, plus a hint of concrete.
Source Atle Mo
Formed by distorting the inside front cover of 'Diversæ insectarum volatilium : icones ad vivum accuratissmè depictæ per celeberrimum pictorem', Jacob Hoefnagel, 1630.
Source Firkin
A rusty grunge background for websites. Feel free to use it in your site's theme.
Source V. Hartikainen
A bit simplified version. Although it could be edited out to be simpler. Anyway, this time the tiling is converted to a pattern fill -which is using clipping for the tile's edges.
Source Lazur URH
This is lovely, just the right amount of subtle noise, lines and textures.
Source Richard Tabor
Submitted in a cream color, but you know how I like it.
Source Devin Holmes
If you want png files of this u can download them here : viscious-speed.deviantart.com/gallery/27635117
Source Viscious-Speed
The tile this fill pattern is based on can be had by using shift+alt+i on the rectangle.
Source Firkin