Thanks Ultimate Chicken, however, that is the location for the 3rd Memory Photo not the 1st.
Whoops, sorry, there's supposed to be 2 in the very first dungeon and I mostly collect chests without seeing which is which. The spike trap hint should be the correct one.
Get to the boss room of the First Cave System/Dungeon. Head the *other way*. That'll deadend in a room with 2 chests. ONE of them will trigger a spike trap (if you've opened both chests before, take note that trapped chests reset and will be closed when you enter the room again). Ride the spike trap up to reach an area with 3 chests. One should contain the photo you're looking for.