I believe it;s a "Patron".
The Goblins Know someone is at the gate because they see bilbos shadow and believe that someone is there. And when Bilbo goes to get threw the gate his brass buttons pop off.
synesthete
Triathlete
movie pirates
a button collector
A catapultist.
onithbfdbvb
I would call him a hobbyist.
dumb
normally .you call one .a letterologist.
a hoarder x)
Graphologist comes to mind or autograph hunter.
Someone with too much time on their hands and too much space?
An aquarist is someone who collects fish in aquariums. They can also simply be called fish keepers. Some collect a variety of fish, while others specialize in a few kinds.
An Arctophile.
A key enthusiast is one way to identify them. There is no actual term to refer to someone who collects keys out of enjoyment, but if they keep the keys out of fear that they may find a use for them after throwing them away, they are potentially a compulsive hoarder.