Bunnies, Rabbits and Lambs
Bunnies, Rabbits and Lambs are often associated with Easter because most babies of the animals are born in Spring around Easter time.
In northern Europe in March, it's the time when hares can be seen running around in the empty fields competing for a mate (although there aren't so many to see now). You might have heard of 'boxing' hares; this is when females are fighting off males - it's not two males fighting!
So it might have been that hares were seen as a spring and Easter animal, especially in Germany and The Netherlands. The earliest record of an Easter rabbit is from 1682 in central Germany where, in a folk story, a rabbit/hare hides eggs in a field for children to find. (But in other parts of Germany it might have been a fox or a stork!)
The 'Easter Bunny' seems to have become more popular when German and Dutch settlers took these folk stories over to the USA.
The Lamb is a symbol of Jesus in the Bible as He was called 'the Lamb of God'. This is because Lambs were and are still used in the Jewish faith as a sacrifice for people's sins and wrong doings. Christians believe that Jesus was killed and sacrificed for everyone.
In many countries, Lamb is eaten as the main Easter Day meal.