Drawn in Paint.net and vectorised in Vector Magic.
Source Firkin
Remixed from an image on Pixabay, the original having been uploaded by darkmoon1968.
Source Firkin
From a drawing in 'Art Embroidery', M.S. Lockwood and E. Glaister, 1878.
Source Firkin
This is a hot one. Small, sharp and unique.
Source GraphicsWall
Prismatic Rounded Squares Grid 4 No Background
Source GDJ
A mid-tone gray pattern with some cement looking texture.
Source Hendrik Lammers
It almost looks a bit blurry, but then again, so are fishes.
Source Petr Šulc
Prismatic Geometric Tessellation Pattern No Background
Source GDJ
A light background pattern with diagonal stripes. Here's a simple light striped background for you.
Source V. Hartikainen
From a drawing in 'Sun Pictures of the Norfolk Broads', Ernest Suffling, 1892.
Source Firkin
Remixed from a drawing in 'Maidenhood; or, the Verge of the Stream', Laura Jewry, 1876.
Source Firkin
A bit of scratched up grayness. Always good.
Source Dmitry
Prismatic Triangular Background Design Mark II 5
Source GDJ
This one could be the shirt of a golf player. Angled lines in different thicknesses.
Source Olivier Pineda
A seamless pattern based on a rectangular tile that can be retrieved in Inkscape by selecting the rectangle and using shift-alt-i.
Source Firkin
A seamless pattern formed from cross 4. To get the original tile select the rectangle in Inkscape and use shift-alt-i.
Source Firkin
Formed by distorting a JPG from PublicDomainPictures
Source Firkin
From a drawing in 'Jardyne's Wife', Charles Wills, 1891.
Source Firkin
Colourful background achieved with gradient fills.
Source Firkin
CC0 and seamless wellington boot pattern.
Source SliverKnight