so...E. 翠菊, 紫菀 spells Easter...in case people didn't know...but they made it out to be different...so whats the E stand for?

I kinda think 你 should ask Bunnymund himself 或者 any really "professional" fan. (I'm kinda am. Haha!) But even I don't know.
Could 你 try posting this 问题 on Rise of the Guardians 粉丝 Club instead? Maybe 你 could get 更多 答案 this way.

I'm not really sure, to be honest. I know there's a book about Rise of the Guardians, so it might be in there 或者 maybe the movie trivia (there might be some on IMDb). I just know its an initial. :) Btw, they were really clever with the names in the movie XD