Simple Trophies adds, uhh... It adds trophies!
The accent color, name, and rotating item they display are fully customizable by your modpack author or server operator. There's two ways to do it - manual NBT editing is one option, but if you don't want to do that, you can build them in-game in Creative mode with... relatively intuitive interactions: right-clicks and anvil renaming.
The mod does not add a way of obtaining the trophies. That's for you to implement yourself, however you like. Trophies are, of course, just plain old items, so any mechanism that can grant items to players can also give them trophies.
Full documentation is on my Github over here, you'd be advised to read it if you are interested in using this mod! I want to keep it all in one place, so they don't get out of sync with each other.
This mod is free software under the Mozilla Public License. Do whatever you want - port it, fork it, repost it, use it in your modpacks - as long as you leave it open source and leave a link to where people can find the source.
Questions? Comments? Just lonely? Join me on Discord: https://quat1024.github.io/discord/