A hint of orange color, and some crossed and embossed lines.
Source Adam Anlauf
Inspired by a drawing in 'Kulturgeschichte', Freidrich Hellwald, 1896.
Source Firkin
From an image on opengameart.org shared by rubberduck.
Source Firkin
Continuing the geometric trend, here is one more.
Source Mike Warner
This is the remix of "plant pattern 02".I changed the object color to white and the BG to purple.The image a seamless pattern derived from a weed which I can't identify.The original weed image is from here:jp.pinterest.com/pin/500744052301423641/
Source Yamachem
This is a hot one. Small, sharp and unique.
Source GraphicsWall
Light square grid pattern, great for a “DIY projects” sort of website, maybe?
Source Rafael Almeida
Sometimes simple really is what you need, and this could fit you well.
Source Factorio.us Collective
Seamless pattern the tile for which can be had by using shift-alt-I on the selected rectangle in Inkscape.
Source Firkin
White handmade paper pattern with small bumps.
Source Marquis
Looks like a technical drawing board: small squares forming a nice grid.
Source We Are Pixel8
One more in the line of patterns inspired by Japanese/Asian styles. Smooth.
Source Kim Ruddock
The texture of this background image has some similarities with leather, and it's colored in a dark brown color. So, if you are looking for a dark brown background image for your website, this may be an option for you.
Source V. Hartikainen