Prismatic Groovy Concentric Background 3 No Black
Source GDJ
Prismatic Abstract Geometric Background 5
Source GDJ
A seamless pattern from a tile drawn in Paint.net and vectorised in Vector Magic
Source Firkin
A seamless pattern based on a square tile that can be retrieved in Inkscape by selecting the rectangle and using shift-alt-i.
Source Firkin
Zerro CC tillable texture of stones photographed and made by me. CC0
Source Sojan Janso
Abstract Tiled Background Extended 12
Source GDJ
Remixed from a drawing in 'The Canadian horticulturist', 1892
Source Firkin
The image depicts a seamless pattern of pine tree leaves.
Source Yamachem
Floral patterns might not be the hottest thing right now, but you never know when you need it!
Source Lauren
This one is quite simple in design, it consists of vertical stripes layered on top of a seamless texture.
Source V. Hartikainen
Remixed from a drawing in 'Chambéry à la fin du XIVe siècle', Timoleon Chapperon, 1863.
Source Firkin
Background Wall, Art Abstract, Block Well & CC0 texture.
Source Ractapopulous
If you want png files of this u can download them here : viscious-speed.deviantart.com/gallery/27635117
Source Viscious-Speed
From a drawing in 'Art Embroidery', M.S. Lockwood and E. Glaister, 1878.
Source Firkin
A free seamless background texture that looks like a brown stone wall.
Source V. Hartikainen
A beautiful dark wood pattern, superbly tiled.
Source Omar Alvarado
I guess this one is inspired by an office. A dark office.
Source Andrés Rigo.
Dare I call this a «flat pattern»? Probably not.
Source Dax Kieran