Green walnuts is the usual name for immature walnuts that are ready for pickling and other uses such as described in Wikipedia.
According to Wikipedia 'In some countries immature nuts in their husks are preserved in vinegar. In England these are called "pickled walnuts" and this is one of the major uses for fresh nuts from small scale plantings. In Armenian cuisine, walnuts are preserved in sugar syrup and eaten whole. In Italy, liqueurs called Nocino and Nocello are flavoured with walnuts, while Salsa di Noci ("Walnut Sauce") is a pasta sauce originating from Liguria. In Georgia, walnuts are ground along with other ingredients to make walnut sauce.'
The green walnut season at Wellwood is short and the best time for picking the green walnuts varies each season.
GREEN WALNUTS ARE NORMALLY ONLY AVAILABLE FOR CUSTOMERS LOCATED IN AUSTRALIA
Sometimes walnuts in shell that have just been picked from the tree and have not been dried are also referred to as "green walnuts" although a better name for them is "wet walnuts". We do not supply those but you may be interested that chef Hugh Fearnley-Whittingstall says that wet walnuts are mild, milky and sweet, with just a hint of that tanic edge that makes walnuts the sophisticate of nuts.