I like to give the player certain items when they did things one way or another.
Lets say your helped Pete grow his carrots, at the end of the quest there might be a scene, which shows Pete saying: "Thank you so much! Here, this carrot is for you. I thought you liked it, because if you look close enough, it kind of looks like you."
Then you get the item, which will always stay in your inventory and can not be used, dropped or sold in any way.
At the end of the game, you will still have the carrot that kinda looks like you. And you would not have had that carrot if you did not help Pete grow any carrots. So, now this carrot can slightly change how the ending will be.
When you are near the end of the game, you can have a scene where all the collected items, like Petes sentimentally valued carrot, each trigger a small scene recalling the memory behind it.
This means, the more unique items you collect, the longer the ending will be. This is different than the other alternative endings, where you can get different scenes, but only one depending on all the choices combined.