Upon peeking into the thread, I see I’m not the only one more than a little creeped out by this.
I wouldn’t do anything until I got a hold of a) the agency, or b) possibly the police.
If someone showed up at midnight in a UPS uniform, I’d be concerned, but our tenant works for a courier service that specializes in panicked-rush delivery of medical supplies at all hours of the day. Whatever’s needed to keep home dialysis equipment running is one of their more popular things, and it’s in plain brown boxes. Of course, those people are anxiously waiting for the package.
It is moments like this that I regret having no internet connection at home. I thought this was going to be a neat puzzle story, but it now appears to be a real neat puzzle story.
I hope no one gets unbalanced.
The suspense is killing me! AAgggghh!
A strongbox, as in a safe? Is it the kind of thing you’d keep the cash from a bake sale in, or the kind of thing you’d keep your grandmother’s diamond jewelry in? Is the box itself something that people would pay good money for?
two things occur to me:
option 1) yes, there are lunatics out there ( gee–can you tell I live in Middle East? 
)
But I wouldnt worry too much about that in Dallas
option 2) more likely–it’s a practical joke from a friend. And it would probably be a very,very good friend.(Otherwise it’s not a joke, it’s just weird.)
So-- you ought to be able to guess which friend, and what the joke might be about, even if you can’t guess the contents of the box.
Result:
option 3- if you can’t answer question number 2, re-read comment number 1 above.
Call the courrier company again and demand to know the sender’s name.
But most important:
Option 4: don’t keep us Dopers in the dark! This sounds like fun
chappacula, I can’t believe you would tell someone not to worry about lunatics in Dallas. You do know that Dallas is in Texas, don’t you?
As a former Dallasite (30+ years there), I can say with assurance that you DO need to worry about lunatics in Dallas. Of course, there’s one less since I left.
“Ok, I’ll take the money. Now what do you do with the box?”
“We put a million dollars in it and send it to someone you’ve never met.”
(Cue evil music.)
Nevermind, I didn’t read the OP carefully enough.
But I’m wondering if the package is the box itself, not the contents inside. Maybe it came from a safe company.
It’s possible that the key will come in a separate delivery. If the contents are the point, it would be foolish to ship them together.
Balance, did a rich relative recently die? Could it be a family heirloom?
Thread subscribed
Did you finally order a Straight Dope coffee mug?
Ohhh good idea.
No No No! You do not want to leave that thing unattended! Don’t you know that as soon as you leave the room the door will slowly open and something Evil[sup]TM[/sup] will slither out?
Better not turn your back on it either!
Ummm…maybe it’s the [del]bitter bastard[/del] cynic in me, but I have a nasty feeling you’re going to get a black-boarded letter from a lawyer, with the key in it. 
Bomb was the first thing to cross my mind. This is eerie. I don’t like it…I don’t.
Dear Mr. Balance,
My name is Gnagetr Octopus from Nigeria. I represent a wealthy family who’s wealth had been kept in an safe deposit box in your city. A compatriot of mine has retrieved the box and upon advice from another colleague I am entrusting it to you at this time. You were recommended as being extremely trustworthy and reliable, which is important because I am asking that you please deliver the box tro me personally in Lagos, I have the key in my posession. The box contains $15 million in jewels and american currency, of which I will give you $6 million for your help. In order to facilitate this transaction I request you send me your banking information so that I may deposit the cash into your account. as well as give you cash at this time for a plane ticket.
In case I wasn’t clear, I think it is a legacy, from a dead friend or relative.
Not that I wish ill, but it seems the most likely explanation.
That’s my guess as well. A letter and key from a lawyer or family member was meant to show up first, but just hasn’t arrived yet.
That doesn’t explain the odd timing of the delivery, though.
Does it rattle?
Whatever it is, I want some. Nobody ever sends me anything.