FreeBSD: Finding Your Application

# whereis lsof
lsof: /usr/ports/sysutils/lsof
This tells us that lsof (a system utility) can be found in the /usr/ports/sysutils/lsof directory.

Additionally, you can use a simple echo(1) statement to find where a port exists in the ports tree. For example:

# echo /usr/ports/*/*lsof*
/usr/ports/sysutils/lsof

http://www.freebsd.org/doc/handbook/ports-finding-applications.html