The name tells you it has curves. Oh yes, it does!
Source Peter Chon
A seamless light gray paper texture with horizontal double lines.
Source V. Hartikainen
Seamless Green Tile Background
Source V. Hartikainen
From a drawing in 'Art Embroidery', M.S. Lockwood and E. Glaister, 1878.
Source Firkin
Dark wooden pattern, given the subtle treatment. based on texture from Cloaks. https://cloaks.deviantart.com
Source Atle Mo
Looks like an old rug or a computer chip.
Source Patutin Sergey
I guess this one is inspired by an office. A dark office.
Source Andrés Rigo.
A playful triangle pattern with different shades of gray.
Source Dimitrie Hoekstra
Drawn in Paint.net and vectorised in Vector Magic.
Source Firkin
Zerro CC tillable texture of stones photographed and made by me. CC0
Source Sojan Janso
Remixed from a design seen on Pixabay. The basic tile can be had by selecting the rectangle in Inkscape and using shift+alt+i.
Source Firkin
A subtle shadowed checkered pattern. Increase the lightness for even more subtle sexiness.
Source Josh Green
A seamless pattern from a tile made from a jpg on Pixabay. To get the tile select the rectangle in Inkscape and use shift-alt-i.
Source Firkin
Simple wide squares with a small indent. Fits all.
Source Petr Šulc.
Sort of like the Photoshop transparent background, but better!
Source Alex Parker
Can never have too many knitting patterns, especially as nice as this.
Source Victoria Spahn
Here I have tried to create something that would look like maple wood. Not sure how well it's turned out, but at least it looks like wood.
Source V. Hartikainen
Seamless Background For Websites. It has a texture similar to cork-board.
Source V. Hartikainen
Abstract Ellipses Background Grayscale
Source GDJ
Floral patterns will never go out of style, so enjoy this one.
Source Lasma
From a drawing in 'Hubert Montreuil, or the Huguenot and the Dragoon', Francisca Ouvry, 1873.
Source Firkin