For a list of state study resources, including printable cards go HERE
Apples are the largest agricultural product in Washington, so we made Easy Apple Delight
And for North Dakota we made North Dakota Dinner (though we ate it for supper). I made it in the crock pot. I try to use the crock pot as much as possible to keep the house cool.
Read some books
This book was great, it talked about a lot of different landmarks in Seattle, we then took to the web and looked up the real life pictures of them. Lots of really neat buildings and statues in Seattle. I finally found these books! They are at a different branch of the library here, so know I pre order them a week ahead. They have small bits for each letter of the alphabet that goes with the state, there are pretty in depth paragraphs that go along with each letter too, but this can be skipped over for the littler guys, I felt like it was too much information for my 5yo.
And of course we added the post cards to our wall map.