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How’s this for a justification to spend absolutely no money on toys this holiday season?

In a Psychology Today post, Gabrielle Principe, a psychology professor and author of Your Brain on Childhood: The Unexpected Side Effect of Classrooms, Ballparks, Family Rooms, and the Minivan, gives her suggestions for the “Five Best Toys for Christmas.”

Principe’s list has nothing in common with the “must-have hot toy” roundups created by retailers and news outlets that are ubiquitous at this time of year. There are no gadgets or Elmos, nothing that comes with instructions or needs batteries. Instead, she offers alternatives to the typical merchandise in the toy aisle, which are all free or nearly free:

Each toy on my list is affordable, appropriate for a wide range of ages, and better than the usual overpriced toys on the retailers’ lists.

So what’s on her list?

Sock

Mud

Ball

Pebbles

Backdoor

All of these “toys” have two things in common: 1) They can be played with in all sorts of ways; the everyday sock, per Principe, “has a built-in flexibility” that “highly structured toys do not,” allowing it to serve as a puppet, or be “used as a purse for dressup, a beanbag for tossing, a tube top for Barbie, a potholder for mudpie baking sheets, a grass sock pet for little brother, and a beer can koozie for dad.” And 2) They’re all readily available without spending a dime because they’re already in your house or backyard.

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Oh, there’s one other thing these items tend to have in common: With the exception of a ball, a Mom or Dad who places such an item under the Christmas tree is likely to be automatically and immediately nominated for the Worst Parent Ever. (Blaming it on Santa might even make matters worse.)

Principe isn’t some absentminded professor with no firsthand knowledge of kids; she’s the mother of an 8-year-old. And yes, all of the items listed are potentially wonderful playthings. But I’d love to see her, or any parent, try to pull off a Christmas morning with only these kinds of items under the tree. Even if you agree that kids today are spoiled and have too many toys, and that most of the toys are garbage—and I personally agree with all of this—nobody is happy with a new pair of socks, let alone an old pair, on Christmas.

The point (I think) isn’t to actually give these items as Christmas gifts, but to think twice about what you buy for kids—and carefully consider whether or not what you buy actually inspires them to learn and use their imaginations, which is a different level of fun than today’s typical sedentary “amuse-me” electronics and playthings.

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For that matter, Principe is hardly the only parent suggesting that the best toys are free things that people don’t think of as toys at all. The list of “5 Best Toys of All Time” from Wired’s GeekDad blog consists of:

Stick

Box

String

Cardboard Tubes

Dirt

Carboard tubes, for instance, “are kind of like the toy at the bottom of a box of Cracker Jacks — they come free with a roll of paper towels and other products but you have to wait until you get to the end of the roll before you can finally claim the toy.”

Alternately, there are ways to wrangle up more traditional toy-type toys without paying full price or being wasteful. A Boston TV station (by way of Consumerist) recently featured Toygaroo.com, a toy rental service in which families pay as little as $25 for a box of four toys that can be exchanged every 60 days. Shipping is included, and toys are sanitized before they’re sent on to the next family.

There are several sites that facilitate toy swaps as well: ThredUp and Zwaggle as examples, though the focus at both of these sources tends to be more on kids’ clothing and gear.

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Perhaps the easiest means of all for getting free “new to you” toys is to find families in your neighborhood who are game to swap from time to time. As any parent who’s attended a play date knows, the most fascinating toy to a child always seems to be the one in someone else’s house.

Brad Tuttle is a reporter at TIME. Find him on Twitter at @bradrtuttle. You can also continue the discussion on TIME’s Facebook page and on Twitter at @TIME.