Other than the dead, rather dehydrated mouse body that I found this morning when doing the weekly cat toy round up?
They love these
Fluff Bunny and these Dust Bunny and those Springy Worm

About the only thing our cat really loves is a laser pointer. He can hear you pick it up across the house and comes running- it has a keychain on it and no matter how quietly you try to pick it up, he hears it. I'm wary of the laser pointer- making sure to keep it away from his eyes as he bounces around and all that, but it is by far his favorite toy, and it wears off his horrendous energy level like nothing else can.

He also likes the little stuffed birds and mice that chirp when they are moved.

throw rugs

my hat

my hair

anything with feathers

the dog

By far the most loved toy of all 4 cats it the plastic milk jug ring!

Twist ties from plastic baggies, milk jug rings, thin strip of cotton cloth torn off my pj's, wadded up newspaper balls, and the hands-down favorite--a cardboard box! No need to ever spend money on a cat toy!

Forgot to add a paper grocery bag.

Ours like the fur covered mice and the plastic springs.

One likes hair bands. None of them like milk carton rings, but they do like the vinegar jug ring.

The other cats

A wine cork "birdie" (cork with a feather stuck into an hole in the cork)

My SO's underwear

The leftover shower water

Here is a link that might be useful: Cheap cat toys

Everybody loves the wand with *tinsel* on the end at my house! Great sound for them. The ones with the feathers and cloth gadgets were a waste.

They don't really care for synthetic. I buy the mice/weasel toys with real rabbit fur.