Here are the places I grabbed my images from. Some directly link to geocities pages, but the exact pages are not listed.

https://gifcities.org/
https://www.geocities.ws/ratusnorvegicus/backgrounds.html
https://emma31.tripod.com/backs.html
https://www.mikesfreegifs.com/
https://www.coin-operated.com/2010/05/01/the-web-museum-1999/
https://www.cameronsworld.net/
https://cooltext.com/