Bingo. I went through a phase when wanted to get a passage from one of my favorite pieces of literature. Then a phase when I wanted a stylized artwork of either a rabbit (fertility) or ravens (the Morrigan, specifically). I may still get one or all of those things, but I settled on a geometric design to begin with because of the beauty and simplicity and universality of mathematics.
Saw these while lurking hildidrawsdicks' blog, but only one was in the main post while the others were just added in the captions and in gray box form. I think they all deserve to be seen in the main post, yes? (source)