Match 3, CC0, textures: 
https://opengameart.org/art-search-advanced?keys=match+3&title=&field_art_tags_tid_op=or&field_art_tags_tid=&name=&field_art_type_tid%5B%5D=9&field_art_type_tid%5B%5D=14&field_art_licenses_tid%5B%5D=4&sort_by=score&sort_order=DESC&items_per_page=24&Collection=

LearnOpenGL:
https://learnopengl.com/