I only know where seven of the berries are.
1.) Dig around in your field.
2.) Keep offering stuff to the harvest goddess everyday until she finally gives you one. (I'm not sure how many days)
3.) Turn in 900 medals at the horse race
4.) Win the horse race
5.) Buy it from the TV shopping network. They will sell it after you bought everything else from the TV shopping network.
6.) When kappa's lake is frozen over, go behind the mine and push A
7.) throw cucumbers in kappa's lake for ten days in a row