From a tile that can be had by selecting the rectangle in Inkscape and using shift+alt+i.
Source Firkin
The image is a seamless pattern of a fishnet.
Source Yamachem
U.S.-based National Fire Protection Association standard fire diamond for flagging risks posed by hazardous materials. The red diamond has a number 0-4 depending on flammability. The blue diamond has a number 0-4 depending on health hazard. The yellow has a number 0-4 depending on reactivity. the white square has a special notice, e.g OX for oxidizer.
Source Firkin
A seamless background colored in pale orange. It has a paper like texture with diagonal grid pattern.
Source V. Hartikainen
Turn your site into a dragon with this great scale pattern.
Source Alex Parker
A seamless pattern the starting point for which was a 'colour modulo' texture in Paint.net.
Source Firkin
From a drawing in 'At home', J. Sowerby, J. Crane and T. Frederick, 1881.
Source Firkin
Prismatic Groovy Concentric Background No Black
Source GDJ
The square tile this is based on can be had by selecting the rectangle in Inkscape and using shift+alt+i
Source Firkin
You know you love wood patterns, so here’s one more.
Source Richard Tabor
It has waves, so make sure you don’t get sea sickness.
Source CoolPatterns
From a drawing in 'Art Embroidery', M.S. Lockwood and E. Glaister, 1878.
Source Firkin
This was formed by distorting an image of a background on Pixabay.
Source Firkin