The R base package contains far too many objects to list here.

You can use
	ls("package:base")
to list all user-level objects in the base package.

Alternatively you can browse the HTML manual by help.start(), and go
to the base section of the `Packages' page. 

Or, look at the DVI or PDF versions of the R object reference manual
in the `${R_HOME}/doc/manual' directory.