One very common complaint is that players end up discarding a lot of items during events because event items take up space in their barn. This is especially true when the required quantities increase during events in which we need to upgrade something (unlike events like the "Without 'Feather' Ado" event that just finished, in which required quantities remained the same throughout). Perhaps we could have a new building (or two) to address this.
First, all event-related materials (and only event-related materials) could be directed into an Event Storehouse. This would only be for items specifically introduced for an event and crafted in new buildings introduced for the event; new recipes making use of regular buildings (e.g., the Mushroom Stew, etc., from the Gnome event) would still go into the Barn. Like the Barn and the Silo, the Event Storehouse would need to have its capacity upgraded; for those high-level players who have fully upgraded everything and unlocked all the spaces in each building's queue, this would provide them with a use for any upgrade parts they have collected but are now selling or discarding because they can't do anything more with them except wait for another increase in capacity to be made available. Because it would be for events only, it may well remain inactive during certain events (e.g., County Fair events), though players would still be able to upgrade even if it is not currently in use.
Second, any excess event-related materials could--if the player chooses--be moved into an Event Showcase or Event Gallery. These would be any event-related items (collected or crafted) that a player chooses to set aside and hold onto as "memorabilia", as a memento of the past event. This is, of course, solely the choice of the player; most players would opt to use everything they craft (and in some cases have no choice since they run out of time and need that last one to finish the event), but a few might appreciate what some of the items look like (e.g., Arctic Fox Plushie) or value them for all the effort that went into it (e.g., Gnome Coin and Mushroom Terrarium). Items could only be moved into the Showcase/Gallery after the event--or perhaps at any time during the event--and once in cannot be removed. This, too, might be like the Barn and Silo and need to be upgraded as time goes on.
Even if the second idea is too far-fetched, please consider the first as being a serious suggestion. Thank you for your time.