All of Canada's centenial coins had different backs and it was at a time when they were normally standard from year to year. Now, we quite often have different coin designs from year to year, especially with quarters and loonies.
In 67, if my memory serves me correctly, the penny had the bird, the nickel had a rabbit, the time had a fish and the quarter had mountain lion (or some similar animal). There is also a 50 piece and a "silver dollar" coin (before the loonie became the replacement for the paper bill) and they had different designs too but since they were not normally circulation coins I don't recall what they had on them.
As far as what it is worth, circulated after all these years...I'd say maybe a penny. Keep it as something different if you want but I could go through a jar of change I have here and find a few of them in there I'm sure.
The penny was issued to commemorate the 100th anniversary of Canada's confederation, which occurred on July 1, 1867. The coins themselves are not especially valuable -- a roll of 50 of them sell on eBay for about a dollar.