I'm glad to see someone else list handkerchiefs. When I used to frequent thrift stores on a more regular basis, I would buy every vintage quality linen pocket handkerchief I could find.
Front left pocket: E1L lego, Spyderco Delica, cell phone (yes, it gets a bit crowded).
Right hip pocket: pocket handkerchief
Front right pocket
Countycomm.com "6" mechanic's cable keychain" with:
pill fob with spare CR123a cell for E1L
Peak LED Solutions Baltic (with lowest output option led)
geocaching container with spare AA lithium cell for Peak Baltic
NiteIze keychain pen
Countycomm.com peanut lighter, with short length of snug-fitting short length of clear polycarbonate tubing to hopefully minimize fuel evaporation
house and car keys
Spyderco Ladybug
Countycomm.com orange whistle
(both the whistle and Ladybug have had very short lengths of brass tubing inserted into the lanyard holes to hopefull delay Countycomm.com keychain cable from abrading all the way through the plastic.)
[Inspector Gadget, though largely forgotten by the public in his twilight years, still tried to help when he could...]