Animal Ears Headbands: Ecofelt is quite affordable, and it is made out of recycled water bottles. Headbands can be bought in bulk. Or.... these could be adapted to be made entirely out of construction paper.
SET Dress Up BARNYARD MASK 6 Piece Set, pretend play for toddlers, preschool, kindergarten. Farm Animal Mask by JamJarDesignShop on Etsy https://www.etsy.com/listing/222845654/set-dress-up-barnyard-mask-6-piece-set