From a drawing in 'Art Embroidery', M.S. Lockwood and E. Glaister, 1878.
Source Firkin
This one takes you back to math class. Classic mathematic board underlay.
Source Josh Green
Recreated from a pattern found in 'Az Osztrák-Magyar Monarchia irásban és képben', 1882. To get the tile this is based on select the rectangle in Inkscape and use shift+alt+i.
Source Firkin
Tiny little fibers making a soft and sweet look.
Source Badhon Ebrahim
Sometimes simple really is what you need, and this could fit you well.
Source Factorio.us Collective
Tiny, tiny 3D cubes. Reminds me of the good old pattern from k10k.
Source Etienne Rallion
Green Web Background, Seamless tile.
Source V. Hartikainen
From a drawing in 'Sun Pictures of the Norfolk Broads', Ernest Suffling, 1892.
Source Firkin
To get the tile this is based on select the rectangle in Inkscape and use shift+alt+i
Source Firkin
Vector version of a png that was uploaded to Pixabay by pencilparker
Source Firkin
Classic 45-degree pattern, light version.
Source Luke McDonald
Remixed from a design on Pixabay. To get the tile this is based on select the rectangle in Inkscape and use shift-alt-i.
Source Firkin
Prismatic Snowflakes Pattern 2 No Background
Source GDJ
From a drawing in 'Art Embroidery', M.S. Lockwood and E. Glaister, 1878.
Source Firkin
Prismatic Abstract Line Art Pattern Background
Source GDJ
This one resembles a black concrete wall when is tiled. It should look great, at least with dark website themes.
Source V. Hartikainen
A seamless background tile of aged paper with shabby look.
Source V. Hartikainen
Derived from a drawing in 'The Murmur of the Shells', Samuel Cowen, 1879.
Source Firkin
The image depicts a seamless pattern of a Japanese family crest called "chidori" in Japanese .A chidori in Japanese means a plover in English.
Source Yamachem
A dark one with geometric shapes and dotted lines.
Source Mohawk Studios
Abstract Tiled Background Extended 8
Source GDJ
The unit cell for this seamless pattern can be had in Inkscape by selecting the rectangle and using shift+alt+i.
Source Firkin