California, Berkeley: Multiple options
Massachusetts, Cambridge: Children’s Clothing Exchange takes all kinds of children’s clothing and toys, used and new.
Michigan, Grand Haven: Toys Are Used acts as a toy exchange for locals, providing credit for used toys brought in, to be used for other toys in the store.
Daycare centers and homeless shelters are always good bets. Keep in mind children’s hospital wards usually accept new toys only, for hygenic reasons.