Hi Foot toys are exactly that, toys that are played with the feet. Anything safe can be used.
Here's a link to show you variety, it's a Canadian supplier though. Foot Toys
What do they like, depends on the bird, mine loves wood blocks and rattles.
Yes, what sandybee said! just toys they can hold in their feet
They are great when they are out of their cage, and just sitting next to you, you can just have a box of foot toys they can rummage through and play with!
Fargo loves all the kinds of foot toys, but his favourite is just wooden blocks off of old toys, because he can destroy them easily and turn them into splinters