The ending of "Raiders of the Lost Ark"
showed this crate being stored in an anonymous warehouse. 
Actually, that was a decoy crate and the real crate has been
safely housed at Patrick's in-laws attic  since the
1930's. 

Well, that is until now.  I won't be surprised if I see an
EBAY or Craig's List posting from "Lord God Almighty"
selling the Grail to the highest bidder.

BONUS:  The crates actually contained extra roof shingles.

In the boxes were grandma's most hideous christmas
decorations from the early 1900's.  When grandma passed away
these were passed on to the oldest daughter who took one look and
just wanted them gone, but afraid that someone in the family
would one day ask what ever happened to grandma's treasured
decorations they were put away in the attic as a just in
case.  Time passed and out of sight meant out of mind so
they just sat there.  The question now is, Is anyone brave
enough to just get rid of them???

Each box was cedar lined.  One box held a
beautiful white wedding gown with intricate pearl beading. 
The second box held a veil, shoes, an amazingly preserved bouquet
of flowers, as well as a wedding album with black an white photos
that were dated from the 1950s, and they were all captioned in
another language.    What Patrick's father-in-law
discovered is that the bride was his very own wife — but the
groom was not himself!

BONUS:  The boxes were actually full of old college books.

The box contains the original business plan for
the Dharma Initiative.  It was left there in 1977 by one of
Charles Widmore's henchmen as he hid from an escaped smoke
monster that somehow got off the Island and was attempting to
destroy Widmore's organization and capture the plans.

Though the Dharma Initiative had been operating for years by that
point, the plan contained crucial information that would allow
the smoke monster to maintain his separation from the Island
permanently (he was going to perish, otherwise, if he did not
return to the island within 48 hours).

Unfortunately for the smoke monster, he was not able to locate
the plan due to its being squirreled away and had to get back to
the island to avoid perishing. 

BONUS: What was really in the box?  Curtains and old
clothes.

The boxes were filled with artifacts from slaves
that had passed through this house on the Underground Railroad
escaping to Canada to free themselves.  There were arm and
leg shackles and old remnants of clothing.  There were even
some diary pages with names of the people who had escaped.

BONUS: They were empty (except for mouse droppings.)

My parents bought house built in 1873 when we
moved to CT in 1986.

One day we had a swarm of hornets in our foyer and called the
exterminator. My parents were at work and my sister and I were
the only one’s home. The exterminator came and checked the attic
to see where the hornets were coming from. He found no hornets in
the main attic, then asked if he could check the second attic.

We knew of no other attic! (Pete {the exterminator} had been in
the house before, to get rid of a family of flying squirrels
years before.)

My sister and I followed Pete to the “second attic” that was in
my parents room, behind built in shelving in their walk in
closet. We had a secret room! As we all crawled in, we saw a box,
and surrounding the box was the swarm of hornets!! They were
eating the box! We all backed out very quickly! Pete said he saw
this before and needed to get something out of his truck. A
minute later we heard the screeching tires of his truck leaving
the driveway! After two cans of Raid, we killed the bugs and got
to the box. The wooden box was coated with dust and old iron
claps. We slowly opened the box. From the edges a glowing mist
seeped out. As we had the box halfway open, an energy forced the
box open! The mist floated above us! Screaming and running faster
than our feet could run, we raced out of the house!