My name is Nick Doran, and I am the former president of the UCSD Casual Golf Club.
I am going to post rules decisions as I encounter them on the golf course. I am pretty sure that I will be able to come up with at least one rule nugget for each round that I play.
You get to the first green, and you realize that you don't have a ball marker. Can you use a leaf or a small pebble?
I don't think you can. The rules define a ball marker as "an artificial object..."