Children's book ID-please help me!

I for some reason just remembered a book I read and loved when I was in elementary school (though I couldnt tell you what grade I was in). It was a book that had two sequels all of which had maps of the islands that were the settings for the three books.

from what i remember of the plot, there was a boy who ran away from home with a backpack full of stuff like chewing gum and toothpaste and then went to the docks and hid in a sack of seeds on a boat that took him to...some other town. from there he crossed a bunch of stepping stones until he reached an island that had a bunch of malicious animals that he was able to distract and pacify by giving them or letting them use some of the objects he put in his bag when he left his home. i remember the ending having all the animals being really pissed at him and all going after him but he was able to make it across the stepping stones leaving them irritated at him from the shore. he made it back to the town where he was able to get into another sack of seeds (or something else of the like...whatever they were).

the sequel involved canaries i think....

anyone have any idea what i'm talking about?