Here are a couple of books that I enjoyed regarding geometry. You can also go through the list of accounts that I follow with my generative art Instagram account to find some cool people/art.
- Islamic Geometric Patterns – Eric Brourg
- How to Make Repeat Patterns: A Guide for Designers, Architects and Artists – Paul Jackson
- Sacred Geometry: Philosophy and Practice – Robert Lawlor
- Brilliant.org (interactive courses)
- Quanta Magazine (cool science blog)
- r/GeometryisNeat