I haven't started my collection yet, but I think I'll start with Canadian coins. Although fairly young, they have a lot of history and are interesting to look at:
1 Canadian dollar coin (commonly known as a Loonie), has changed its design in 1987 to have a picture of a Loon. Apparently, the coin with a picture of Voyageur (a canoe) was replaced by the bird because the master dies were stolen (Wikipedia says that they were lost by the courier service, but a more reliable source tells me that they were stolen).
So this is the original one:
and the new one:
Also (in case you aren't from Canada), the queen on the back of the coin gets older on the new coins that are released.
