Palms, coconuts, maybe things like shells, starfish, etc (beach debris for jungle islands). Pit traps with or without stakes in them, huts on stilts (or some way to make them), volcanic rock (columnar basalt? magma, volcanic stuff - thinking Hawaii).
Tropical trees, cacti, adobe buildings, bamboo/log and leaf buildings, blowdarts, clubs, etc. Just stuff for Jungles and Deserts.