An abstract texture of water. It's not perfect, but will do. You may download if you like it.
Source V. Hartikainen
Prismatic Floral Pattern 3 Variation 3 No Background
Source GDJ
A free seamless background texture that looks like a brown stone wall.
Source V. Hartikainen
Nothing like a clean set of bed sheets, huh?
Source Badhon Ebrahim
Inspired by a drawing seen in 'City of Liverpool', James Picton, 1883.
Source Firkin
A seamless texture traced from an image on opengameart.org shared by Scouser.
Source Firkin
The image depicts a pattern of regular hexagon.As I made to use it for myself,I want to others to use it.Speaking about the ratio of the image, height : width = 2 : √3(1.732...)Ridiculous to say,I realized later that this image is not honey comb pattern.I have to slide the second row.
Source Yamachem
From a drawing in 'Sun Pictures of the Norfolk Broads', Ernest Suffling, 1892.
Source Firkin
Dark squares with some virus-looking dots in the grid.
Source Hugo Loning
Abstract Arbitrary Geometric Background derived from an image on Pixabay.
Source GDJ
A seamless chequerboard pattern formed from a tile that can be had in Inkscape by selecting the rectangle and using shift+alt+i. Alternative colour scheme.
Source Firkin
A seamless pattern with wide vertical stripes colored in pale yellow.
Source V. Hartikainen
Vector version of a png that was uploaded to Pixabay by pencilparker
Source Firkin
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
Used correctly, this could be nice. Used in a bad way, all hell will break loose.
Source Atle Mo
A free light orange brown wallpaper with vertical stripes designed for use as a tiled background on websites. An yet another background pattern with vertical stripes.
Source V. Hartikainen
Dare I call this a «flat pattern»? Probably not.
Source Dax Kieran
First pattern tailor-made for Retina, with many more to come. All the old ones are upscaled, in case you want to re-download.
Source Atle Mo