Inspired by the B&O Play, I had to make this pattern.
Source Atle Mo
Prismatic Geometric Pattern Background 2
Source GDJ
From a design found in 'History of the Virginia Company of London; with letters to and from the first Colony, never before printed', Edward Neill, 1869.
Source Firkin
Retro Circles Background 8 No Black
Source GDJ
Prismatic Curved Diamond Pattern 4 No Background
Source GDJ
This one takes you back to math class. Classic mathematic board underlay.
Source Josh Green
Derived from a drawing in 'The Murmur of the Shells', Samuel Cowen, 1879.
Source Firkin
Looks like an old rug or a computer chip.
Source Patutin Sergey
Subtle scratches on a light gray background.
Source Andrey Ovcharov
From a drawing in 'Art Embroidery', M.S. Lockwood and E. Glaister, 1878.
Source Firkin
Prismatic Abstract Geometric Background 4 No Black
Source GDJ
Super dark, crisp and detailed. And a Kill Bill reference.
Source Badhon Ebrahim
Here's a camo print with more tan and less green, such as might be used in a desert scenario. This is tileable, so it can be used as a wallpaper or background.
Source Eady
The tile for this is based on a repeating unit close to a design on Pixabay. It can be had by selecting the rectangle in Inkscape and using shift-alt-i.
Source Firkin
From a drawing in 'Danmarks Riges Historie af J. Steenstrup, Kr. Erslev, A. Heise, V. Mollerup, J. A. Fridericia, E. Holm, A. D. Jørgensen', 1897.
Source Firkin
A repeating background with dark brown stone-like texture and abstract pattern that looks like tree trunks.
Source V. Hartikainen
A seamless chequerboard pattern formed from a tile that can be had in Inkscape by selecting the rectangle and using shift+alt+i. Alternative colour scheme.
Source Firkin
From a drawing in 'Art Embroidery', M.S. Lockwood and E. Glaister, 1878.
Source Firkin
Remixed from a drawing in 'Очерки Русской Исторіи въ памятникахъ быта', Petr Polevoi, 1879.
Source Firkin
Prismatic Hexagonalist Pattern No Background
Source GDJ
Seamless pattern formed from a tile that can be extracted by selecting the rectangle in Inkscape and using shift-alt-i.
Source Firkin
A seamless pattern formed from a tile made from page ornament 22. To get the tile, select the rectangle in Inkscape and use shift+alt+i.
Source Firkin
This one is quite simple in design, it consists of vertical stripes layered on top of a seamless texture.
Source V. Hartikainen
Pass parameters to the URL or edit the source code variables to configure the graph paper for the division desired.
Source JayNick
Number five from the same submitter, makes my job easy.
Source Dima Shiper
The tile this is based on can be had by selecting the rectangle in Inkscape and using shift+alt+i
Source Firkin
Beautiful dark noise pattern with some dust and grunge.
Source Vincent Klaiber