Inspired by this question that was asked by Ibetit in the "is this rude behavior?" thread, I thought I'd give it a thread of it's own.
Some good replies to that question so far in the other thread by
Whoopsydaisydoodles: Matching Cutlery and Lawnmower,
and also by
Jimgoose: a stick for mixing paint and lots of spare pillowcases.

I'm lacking a lawnmower from those suggestions, and not all of my cutlery matches, nor do all my pillowcases match either come to think of it.
I will add to the list:
One of those coin shaped things on your keyring for shopping trolleys.
Candles incase electricity goes out.
[I haven't gotten around to getting these yet but keep thinking that I probably should, they never would have crossed my mind when younger.]