My cat, many years ago, liked to play with rolled-up balls of cigarette foil. She would fetch them for hours. When we vacuumed under the couch we found like 20 balls of rolled-up foil that she’d lost under there.
My mom’s old cat used to fetch pom-poms - the large ones you buy for crafts. One morning a pom-pom fell into his water dish so he picked it out and woke my mom up by putting the wet pom-pom on her face.
The most famous and unexpected one of all time has to be the red dot as it is know in the feline world, to humans it is known as the laser pointer.
I’ve never met a cat who won’t try to murder the laser-bug, but we used to have a dog who did it, too. She was a St Bernard. Envision about 130lbs of cow-spotted dog, lumbering around the house, wrinkles of skin hiding her eyes because her nose is aimed straight down, trying to smash the red dot with her enormous showshoe feet.
I keep rats these days, and they don’t fetch very well – they can’t see for beans, and they prefer to steal food that doesn’t move anyway. They do like my cloth-wrapped rubber ponytail elastics, though. Apparently they’re sproingy to chew on, and occasionally I’ll get one to play tug-of-war with me.
When my first cat had a litter of kittens, I made a bed for them out of a couple of worn-out old t-shirts. Unwashed, like the books said.
When the kittens got old enough to be crawling around, they used to climb up the recliner (or my legs), lay on my chest, stick their heads into my armpit, and fall asleep. Took me a while before I figured out why they were doing that!
My cat likes what we jokingly refer to as the ‘stinky foot place’ - as I spend a fair amount of time in bed when I am stuck having a bad body day/week/month, she likes to curl up next to my feet which is also right next to where the computer desk is when I am able to be sitting for long periods of time so in her eyes it is the perfect place to curl up to be next to mommy without having to move if she were on my lap. I think it is also why you find cats or kittens who sleep with their heads in shoes.
I’ve had two cats in a row who were fascinated with my shoes. With our previous cat, Felix, when he had to spend a couple of days in the kitty hospital for a bladder blockage, he got a pair of my socks to cuddle with in his hospital cage (he apparently did appreciate it).
Prowler loves her “snakes” - I got some rubber therapy tubes for PT arm exercises, about as big around as your little finger, a different density and elasticity to each one. They’re chewy and sproingy and fun to drag around and run after, probably the #1 non-toy toy in this house.
After reading about the milk ring fetish for most cats, I finally bought a different type of milk than usual to see if it was universal. Sure enough, she’s mad for those milk rings too. Already lost it, of course.
The milk ring is not lost. It is under the refrigerator. If you keep buying that brand of milk you can have an amazing ring collection under there.
I’ve already commissioned more milk rings from co-workers and my man friend…should be able to stockpile a few. 
I know where ALL of the missing toys are: under the bed. It’s a platform bed with storage drawers from IKEA - somehow she shoves them all through a little tiny slot at the foot of the bed. I have to remove the drawers and use the vacuum with a stocking over it to pull them all out.
This is what I found last time:
I have a basket that I put the toys in as I come across them. Sometimes both cats sit there next to the basket, trying to decide what to pick up next; they look just like me in front of the refrigerator!
Sometimes they line their toys up in a row. I always wonder what that’s about…
And if the food dish is empty, little girl kitty puts a toy in it. Payment, I assume.
The dog likes to play with my socks, hats and Bose headphones.
Jerk.
I like the head of the cat in that picture - “Hey, I thought I lost all of these!” 
Golf wiffle balls, especially the orange ones. Cats love them because not only can they chase them around like regular balls, but they can bite them, pick them up and carry them around, and not get hurt if you throw them and they bounce off the wall and hit the cat. They also don’t go soggy when dropped in the water dish.
Speaking of that, Maggie loves playing in water. I had to learn to leave the toilet lid down at all times or I walk in there to water everywhere. The best is taking a small dish with a little bit of water in it and dropping in 3-4 ice cubes. She’ll play with that endlessly until either the ice is gone, or all been pulled out and knocked under things where she can’t get to them. She loves it so much that every time I go to the freezer, she’s right there asking for ice cubes.
Given that it is winter and my apartment is kind of dry, the incidental water from the splashing around and the melting ice doesn’t last all that long. I also wear sandals in my apartment, so I’m never stepping in it.
And yeah, milk rings and rings from pop bottles are all good.
Exactly. “I was looking for these!!”
Chimera, I had a cat who liked water and ice too. If you dropped an ice cube on the tile floor he played hockey with it. He also loved it if you put the water in the sink on just a trickle and then let him drink from it. You might try that on Maggie.
Oh yeah. The bathtub faucet has started to leak again (only had it fixed 3 times in the 4.5 years I’ve lived here) and she drinks from that more than her water dish.
If I get back to owning a house and yard, I’m definitely going to have to build a water feature in the back yard.
On Palm Sunday, our cat would go crazy when we’d waive the palms we’d brought home in front of him!
Both my current cat (female, spayed as a kitten) and her predecessor (male, neutered at about two years old) seem to consider my bras primo kitty toys.
We have this toy mouse that came with a small plastic ring attached to it by a piece of thick string. On a whim, I tied an old bathrobe belt to the ring, at which point it became our cat Molly’s favorite toy. She loves to drag it around the house, usually just dropping wherever she feels would be best and announcing it with a loud meow. For example, like this:
(This picture represents one night’s work–granted, a busier than usual night, but still.)
Occasionally she brings it up onto the bed, and once in awhile she’ll follow this up by carefully pulling the bathrobe belt up after her, by grabbing a bit in her mouth and swinging it sideways with her head, then grabbing the next bit of it, and so on…like an old-time sailor gathering in fathoms of rope.
Which is probably how she managed to do this:
If we’re talking about self-discovered pet toys, then I don’t have anything to add.
Otherwise, I haven’t met a dog that doesn’t love playing tug-of-war with an old belt.
