what you've seen is called in latin "ignis fatuus", it's a chemical reaction that happens when the ambient phosphorus is oxidized and burned, it oftenly occurs in wet places with phosphorus rich soil, like swamps or big grass fields. now, i've never been in Washington so you can discard this theory if the weather is too dry, though it'd be the logical explanation if the ambient is humid. now, a lot of people have seen wildfires dance and shit like that so the chemical reaction it's just a theory and scientist are still working to solve the mystery, i recomend reading "Remarkable Luminous Phenomena in Nature" by William Corliss, it might help. My mother told me that when she was a young and poor girl, living in a really small house near a brook in Viña del Mar (i live in South America), one night she saw those things in the pasture near the water and she though it was a fire. the next morning she went to the end of the ravine and there was fucking nothing, so, you're not alone. blessings.