Then there are socks and, specifically, children's socks. These seem to rearrange themselves, by incorrect size and mismatched colour, on a weekly basis. "Whose is this?" I demand, holding up a sad green specimen that I have never seen before. The seven-year-old shrugs.
I give up after a while. After all, life is too short to track your children's socks (though I'm always surprised that a university department hasn't spent a lot of time and trouble studying precisely that).
Carrier bags also have strange habits. "I thought you might be interested to know that, having just returned from 16 days in Outer Mongolia ... every other person was carrying one of your yellow plastic carrier bags," writes Mrs D Alvis to Sainsbury's Magazine. It turns out that the bags, some of which were four years old, are greatly coveted in Ulan Bator.
No one has written in to report how many trolleys can be found roaming the streets of Mongolia, but surely it can only be a matter of time. Sainsbury's says about 10 per cent of its 250,000 trolleys go missing every year. At an average price of pounds 50 each, this is not a cheap problem. (Tesco is trying to stop this by installing the trolley equivalent of cattle grids around their superstores.)
But at least trolleys that do escape are predictable. Their first love is obviously water. If they can find a canal or a river, they will jump.
And here is another thing: why do all abandoned trolleys look alike? They are all the boring, old-fashioned kind. Yet these days there are so many other options for every lifestyle. There is single-baby, twin- baby, single-toddler, twin-toddler and - yes - baby-and-toddler. There are trolleys for old people and people with bad backs and the disabled and ones for little kids to push, too.
Clares Merchandise Handling Equipment in Wells, Somerset, makes most of the trolleys in the UK and does about 60 kinds. Most are variations in size on the basic 12 or so styles, but not all. "We've just made a shopping trolley for pregnant women with a curve at the back, giving them room for their tummies," says the sales director, Ian Fletcher. "And we've just made a special one for a lady who has given birth to quads."
All of this makes me think that it is too boring that I use an old-fashioned trolley. Isn't it time that we single parents had our own trolley too? It's the kind of thing a university is probably starting to research right now.