I'm still  waiting for my envelope and they continue to call.  Although they did tell me then that now that they are sending me the envelope I will not receive any more calls... but they continue to call CONSTANTLY.

Since this "charity" is rated "F" by the Better Business Bureau I would mail the envelope back empty, except for a note stating "nice try at scamming me". (But only if the envelope is self-addressed, stamped) --they aren't even worth a first class stamp!.

Do not send these crooks any money!  If the envelope is already stamped, then follow the advice above.  Otherwise, next time they call, tell them you cannot give them anything and to please stop calling.  Document the day/time of this request.  

WHEN they call back, stop their sales script immediately and tell them that you are now reporting them to www.donotcall.gov since they have violated your do not call request.  Again, document this request.

WHEN they call back after this, tell them that they will now be reported to your state's Attorney General.  Again, document this request to stop calling.

IF they call back after that, report them to your phone company.  IF they call back again, report them to the police!

If you feel the need to give to charity, go to your local hospital and make a donation directly instead of going through a scammer. There, problems solved.

Caller id said Children's Recovery Center.  Why can't they leave a message?