Dare I call this a «flat pattern»? Probably not.
Source Dax Kieran
Adapted heavily from a JPG that was uploaded to Pixabay by Viscious-Speed.
Source Firkin
Original seamless pattern with an Inkscape filter.
Source Firkin
From a drawing in 'Artists and Arabs', Henry Blackburn, 1868.
Source Firkin
Number 5 in a series of 5 beautiful patterns. Can be found in colors on the submitter’s website.
Source Janos Koos
The perfect pattern for all your blogs about type, or type-related matters.
Source Atle Mo
This white background pattern has a seamless grunge style texture. Here's a white grunge style background pattern. Use it as a tiled background image on web sites or for other purposes.
Source V. Hartikainen
The tile this is formed from can be retrieved in Inkscape by selecting the rectangle and using shift+alt+i
Source Firkin
Remixed from a drawing in 'Prehistoric Man: researches into the origin of civilisation in the old and the new world', Daniel Wilson, 1876.
Source Firkin
From a drawing in 'Sun Pictures of the Norfolk Broads', Ernest Suffling, 1892.
Source Firkin
From a drawing in 'Sun Pictures of the Norfolk Broads', Ernest Suffling, 1892.
Source Firkin
Psychedelic Geometric Background No Black
Source GDJ
Prismatic Snowflakes Pattern No Background
Source GDJ
A dark gray, sandy pattern with small light dots, and some angled strokes.
Source Atle Mo
A seamless pattern the unit cell for which can be had by selecting the rectangle in Inkscape and using shift+alt+i.
Source Firkin
Utilising some flowers from Almeidah. To get the unit tile, select the rectangle in Inkscape and use shift-alt-i.
Source Firkin
Here's an yet another background for websites, with a seamless texture of wood planks this time.
Source V. Hartikainen
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