Granny square source book, if you have to get one book it’s this one https://www.amazon.com/Ultimate-Granny-Square-Sourcebook-Contemporary/dp/9491643290/ref=asc_df_9491643290/?tag=hyprod-20&linkCode=df0&hvadid=385629069539&hvpos=&hvnetw=g&hvrand=7491915861311636975&hvpone=&hvptwo=&hvqmt=&hvdev=m&hvdvcmdl=&hvlocint=&hvlocphy=9032181&hvtargid=pla-816187416470&psc=1&tag=&ref=&adgrpid=78303888466&hvpone=&hvptwo=&hvadid=385629069539&hvpos=&hvnetw=g&hvrand=7491915861311636975&hvqmt=&hvdev=m&hvdvcmdl=&hvlocint=&hvlocphy=9032181&hvtargid=pla-816187416470
I picked up a couple from Amazon that are very good.
https://www.amazon.com/gp/product/9491643290/ref=ppx_yo_dt_b_search_asin_title?ie=UTF8&psc=1
https://www.amazon.com/gp/product/1570769540/ref=ppx_yo_dt_b_search_asin_title?ie=UTF8&psc=1
https://www.amazon.com/Ultimate-Granny-Square-Sourcebook-Contemporary/dp/9491643290
I like this one, saw it recommend in this sub awhile ago, and bought it.
Pattern from The Ultimate Granny Square Sourcebook (https://www.amazon.com/Ultimate-Granny-Square-Sourcebook-Contemporary/dp/9491643290/ref=cm_cr_arp_d_product_top?ie=UTF8); yarn is from Mira Handcrafts (got a package of a bunch of colors specifically for working through this book: https://www.amazon.com/gp/product/B071FXLL5C/ref=ppx_yo_dt_b_asin_title_o00_s00?ie=UTF8&psc=1)