I found large eggs all over town but settled on some from Wal-Mart that were filled with Pop Rocks. They were only $1.00 each compared to $3.00 or 4.00. I mailed out ten so went with the cheapest option that was large enough to stuff a few things in.
We filled them with little candies, trinkets, and stickers.
Then we taped them up mailed them off to our cousins and friends.
The postal workers got a kick out of seeing them there. They told me they've seen things much more odd than Easter eggs come through there.
The same week, my kids received Easter / Birthday packages in the mail throughout the week. One of their favorites was this one: