It's customary for men to have at least three pockets at any given time (two side pockets on the trousers and one breast pocket in the jacket). Gentlemen will fill their pockets with a wide variety of different goods. This article will take a shot at listing the quintessential pocket gear of the average dandy, if there is such a thing as an 'average dandy'.
Front Trouser Pockets
Tobacco & Pipe
Monogrammed Handkerchief (sometimes tucked into coat sleeve)
Pocket Watch with Chain (can be carried in front trouser pockets if waistcoat is lacking)
Inside Jacket Pocket
Wallet containing at least £15 (approx. $30) cash just in case
Fountain Pen (stored upright to avoid leaking)
Of course, one might also carry chapstick and perhaps breath mints and one's mobile if one must. We don't recommend carrying loose coins if it can be avoided; a gentlmen should be known for looking dashing and being well-mannered, not for jingling when he walks.