Horse Chestnuts - Quarter Size - Twenty-Five Nuts The horse chestnut has a rich, mellow, warm-brown shell highlighted by a beige eye. They are great for making necklaces, other jewelry and craft projects. In Great Britain and Ireland horse chestnuts are used for the popular children's game Conkers. Horse chestnuts are slightly poisonous and should be kept away from children and pets. These horse chestnuts have been thoroughly cleaned and dried and are not for planting.