How to display a method's "Ruby Stack Path"

I am trying to learn the Ruby behind Rails and it would be helpful to
be able to find the Ruby code for a given method.
For example I am in Script/console and I do: "puts
ActiveRecord.methods". I get a nice list.
Lets say I want to explore the mattr_accessor method. Is there a
command or method that would give me the Stack Trace to that piece of
Ruby code?
I am using Windows Grep to find it now and that doesn't usually work
as many of the methods are added via class_eval from somewhere far far
away.

it turns up in:
C:\ruby\lib\ruby\gems\1.8\gems\activesupport-2.0.2\lib\active_support
\core_ext\module\attribute_accessors.rb

Typing in some Ruby Magic like ActiveRecord.mattr_accessor.ruby_path
would be really cool. But, I suppose the methods added by "included"
callbacks are going to be invisible... Tell me it isn't so!

Thanks in advance