My MIL has the same packrat gene as your MIL, although not nearly to the extent as your MIL. This past weekend, she offered to make us sandwiches. SIL noticed the expiration date on the lunchmeat was close to 2 years old. SIL asked MIL if the meat had been in the freezer. MIL freaked out and swore it was "brand new" and that the date was just wrong. (Ranting and raving the whole time). MIL proceded to make a platter of sandwiches and couldn't figure out why no one was eating them. Maybe because they made the entire house stink of rotting flesh once she opened the plastic package?