Keep "soup greens" once done cooking?
Polish-style soups typically keep all the vegetables used for cooking. You may do the same with veggies as with mushrooms - chop and drop back into the soup. An exception done by some is parsnip root. 

Unless... it is Christmas-eve mushroom soup (eg. from Mazowsze, central Poland) - then you grind the vegetables into the dumplings mushroom filling. The dumplings are served in the soup anyway.