"You know those rock pockets?" my eldest son said a couple of years ago. I did not.
"What are they?" I asked him.
"Pockets with rocks in them," he replied.
Of course. Silly me. I should have guessed because, at the time, all of his pockets had rocks in them. And so did our washing machine.
My younger son, Joe, had a brief flirtation with rocks, but it's sticks that really make his heart beat faster. There are sticks in all my handbags. The boot of the car is full of them. We put a bucket outside our front door to try to convince him to stop bringing them into the house.
And it's not just sticks. No. He hates me to throw anything away. He cried just yesterday when his dad binned a chicken bone from his dinner and a receipt Joe had already rescued from the recycling.
In fact, 'checking' the recycling is one of his favourite pastimes. We can't throw out egg or cereal boxes, magazines or milk cartons and that's on top of the toys (even broken toys), games, books and other sundry junk he refuses to even consider getting rid of.
Many of my friends have the same problem. Kelly said her son will save anything, "From tiny pieces of paper to baby books. Binders full of magazines, loads of cuddly toys. Everything has to be put in the loft - he gets very upset if anything is binned or charity shopped. I did manage to wean him off collecting elastic bands dropped by the postie..."
Claire, mum to four-year-old Evie, said "We have at least 10 'telescopes' (insides of a roll of wrapping paper) and a box full of mouldy conkers which she refuses to throw away. The best - or worst - was the pocket full of leaves that she insisted on keeping."
I was glad to learn it's not just my kids, but what's it about? Why are children so determined to hoard random bits of rubbish?
Chartered Psychologist Dr Jacqueline Christodoulou is keen to point out that there's a distinct difference between hoarding and collecting. "The word 'hoarding' has become popular more recently because of TV and other media focused on people whose hoarding is out of control," she says.
"It's really important, especially when considering children's behaviour, to differentiate between the two and not to demonise collecting. Where collecting is usually associated with memories of things we like or interest us, and positive emotions, hoarding is more to do with negative emotions and obsession with objects."
There's also a strong component of imagination in collecting, Psychologist Erin Hitzke says: "Collecting is often about the story we create around an object."
This is certainly true of my older son who once burst into tears because I was about to spend a £1 coin he'd 'adopted' and named 'Poundy'. It's the same for Joanne's nine-year-old daugher, Lily, who was embarrassed to admit that she collects because she thinks the things might be 'real'. "Not really real," Joanne says, "she knows straws/shells/bits of masonry on the beach aren't sentient beings, but... just in case."
There's certainly also an element of sentimentality and nostalgia. One of the things that's surprised me the most about my children is how nostalgic they are. I always thought that was something that came with age, but apparently not.
Lily told her mum that part of the reason she collects is as a reminder of the good times "like if we've been to a restaurant and I've chewed a straw, I might want to chew that straw again."
Michelle's eight-year-old son feels the same way about his old shoes. "He used to cry whenever we bought him new shoes," Michelle says. "He always wanted to keep them because he had good memories in them. They were the only things he was really sentimental about so we kept them."
While it's lovely that the children want to keep tight hold of their good memories, we can't be expected to just let our homes fill up with leaves, rocks, sticks, cardboard boxes and old shoes, can we? So what should we do?
One thing I've started doing with my boys is taking photos of the things they don't want to get rid of and telling them the photo is as good a memory as the thing itself. You don't need to keep the physical item to keep the memory.
"Lily has commandeered a portion of the sideboard where I let her keep her 'precious' stuff," Joanne says. "I let it build up and then, when it gets to the point where she opens the door and stuff spills out, I have a cull when she's at school - taking care to chuck the perishable/least interesting looking things."
I've done the same with Joe's stuff in the past, but I was concerned that getting rid of it while he's not there could create trust issues. Parenting expert Liat Hughes Joshi agrees that it's probably not a good idea to throw stuff away behind the child's back.
"Either openly swap the hoarded stuff for something else (of low value) or get them to agree that there's a limit and when, say, two boxes are full, you have to get rid of some of it," Liat says.
"There may be tears or tantrums as a consequence, but as long as you are kind in your approach, they will calm down and get used to the idea that there's a limit to the amount of stuff that can reasonably be kept!"
Dr Christodoulou agrees: "Behaving empathetically by putting yourself in the child's shoes may also help - after all, how would you feel if you arrived home and someone had thrown out a collection, supposedly in your best interests, to tidy up or to make more space? Would you trust this person afterwards? Discussing relocation or reduction of the collection will demonstrate compromise and choice to children. Discussing the collection with your child may even help you to understand their motivations better. "
I agree. Why wouldn't we want to collect thing we like and are precious to us? And who are we to decide what our children find precious. As my sons would say, maybe we just don't understand the magic of sticks.
What 'odd' things do your children insist on keeping?
Do you wish your parents had held on to these?