The first opportunity to do this is in the hidden squirrel cave in Wassail Orchard, but I think that it is easier to do at the end of the chapter. Just before you reach the bookmark for the next chapter, Maypole Fields, you will come across the only “extra thing to do”. Here, there are two squirrels throwing apples around. In the field before this are three acorns.
You need to be really quick for this. Open the camera and buy the Sepia filter; it is the second filter above the default option on the right and will cost 100 confetti. Make sure that it is selected as the filter that you are using before you close the camera. Pick up an acorn and throw it to the squirrel. Quickly open the camera and take a photo as you only have around 3-4 seconds before the squirrel finishes eating the acorn. It doesn’t matter if the picture is blurry, you will still get the trophy.
If you run out of acorns before being able to take the picture, just reload the Maypole Fields bookmark and head back into the fields to try again.