Where can I find more information on the lore of these creatures? The source could be for any edition because I'm not looking for stats.
Canonfire! has a good Bullywug article with an extensive bibliography that should list all the early-D&D sources of info on bullywugs.
More recently, Pathfinder has renamed the bullywug the "boggard" due to IP concerns and has used them extensively, see this wiki article and its references but especially the "Ecology of the Boggard" in the Kingmaker adventure path. All this information has the virtue of being in print and easily obtainable, though any crunch will be 3.5 compatible and not 4e compatible.
Bullywugs were introduced in the Fiend Folio. (First Edition AD&D). A colony of Bullywugs was described in the 1st edition AD&D module I6: Dwellers of the Forbidden City. (Thanks to Lexible for jogging my memory). FWIW, they did make it into Fifth Edition's Monster Manual, if you have that available as a resource. There are a few paragraphs of lore discussion in the monster description.
You may wish to investigate that volume to go back to their original concept, but they did stay in the game through 4th edition. Wikipedia's entry on the monster is a good starting point. If you have access to White Dwarf magazine, you can find some more lore there.