The Stonewall Attack...
https://www.chess.com/blog/RussBell/stonewall-attack
it's relatively straightforward and "easy" to learn compared to other 1.d4 openings....a good opening to learn prior to learning the London System.
Another interesting one would be the Trompowsky Attack....also relatively straightforward...
https://en.wikipedia.org/wiki/Trompowsky_Attack
Also the Colle System, particularly the Colle-Zukertort variation...
https://en.wikipedia.org/wiki/Colle_System
all of the above are interesting.
Chess Openings Resources for Beginners and Beyond...
https://www.chess.com/blog/RussBell/openings-resources-for-beginners-and-beyond
https://www.chess.com/blog/RussBell
I'm starting to play d4 and I'm looking for good openings to start! Any recommendations other than Queen's Gambit and London System? Thanks for the help