Easter eggs full of flour sound like they would hurt if someone got hit with one.
No more than one of these would:
http://theawesomer.com/quanum-rc-bo.../theawesomer.com/quanum-rc-bomb-system/25749/
However, I'll throw out a crazy idea... (I haven't tried it, but it popped into my head as soon as I read "Easter eggs full of flower.")
When I was a kid, we used to punch a small nail hole in each end of a real egg and blow the contents out through one of the holes -- leaving us with empty egg shells we would color and hang on a tree (and providing my mother with a bunch of pre-scrambled eggs for breakfast cooking).
Now, imagine doing this and then taping over one hole, funnel flower (or other powder) into the top hole, then taping over that hole. That would leave you with a lightweight (and easily breakable) container filled with powder -- would probably make a very satisfying "Poof" when it hits the ground. Being so light and breakable, would probably not injure someone too badly if your drop was off-target. The worst that could happen is being struck by a ... (dare I say it?) ... shell fragment (yup, I dared).
Maybe this could be used with the FT Gang's Breakfast Bombers?