Are you talking about when kids leave or just a general thank you to parents just because.

I don't do any type of thank you to parents. Personally all the crafts, mother's day, father's day stuff we send home is enough. I have cupcakes here for the kids birthday's, buy each child a Christmas gift, had santa come to daycare and sent photos home with the kids and buy a gift when anyone leaves care. I am always buying new toys. I don't see any need to thank clients, I think they would rather I spend money on things that will benefit their child everyday.