I second the fruit in Hood River, especially the peaches. Also, a little known orchard jewel is Kimberly, Oregon. Their cherries are top notch.
Any iconic Oregon dessert has to include a minimum of one of the following:
The dessert can be pie, ice cream, cobbler, cake, tart, beer
, but it will have one, or multiple, of the above.
The Marionberry is the most unique to Oregon because it is a blackberry hybred cultivator developed at Oregon State. It is a sweeter and less tart blackberry with a lighter color purple and a lot nicer to pick because of less thorns. It is the "Cabernet of Blackberries." It has been proposed as the state berry since 2009, but has been blocked by rival berry producers.
To cover all the bases in Oregon ingredients, I recommend the Tillamook Diary in Tillamook, Oregon, where all of the above are found in one, or multiple, ice creams; most of which are titled with "Oregon ..." A few years back, they had the "Oregon 150" (statehood) for a short time. It was honey base icecream with hazelnuts and huckleberry drizzle Mmmm!
Oh and they have plenty of room to park an Airstream, that is if I haven't taken the last spot in the usually full parking lot
It is one of the few crowded tourist stops that many Oregonians are willing to brave. In contrast, you won't see me in a line waiting for a Voodoo Doughnut, nor racing for a plane with a pink box (Voodoo again).
To be fair, Umpqua Ice Cream, several other smaller brands, and craft handmade ice creams are available all over the state with a huge variety of the above ingredients.