Post box hunts
I included a photograph of an Elizabeth II lamp box when I posted Coronavirus walk 176 to Imgur, mostly because its bright red colour stood out on an overcast day. A response to a comment made regarding the royal cyphers ultimately led me to realise that I had been overlooking post boxes and all their variety. I started paying more attention on subsequent walks, and later began collecting the photos together under a new post boxes section.
This in turn led to walks where I specifically went looking for post boxes. The term “post box hunt” refers back to pylon hunts.