The main character will know how to start a campfire in the rain, but from what I can remember from my camping days we always used pine needles, small branches from pine trees, and pine sap covered pine bark to start fires in the rain. After some googling (starting fire rain fruit wood, in multiple combinations) I found that's how most people start fires in the rain.
So, if my character is in an old apple orchard rather than a pine forest, does that change how she starts her fire? There is plenty of bramble and undergrowth, but I'm not sure how much of it would be dry under fruit trees verses pine trees and how many dry smaller branches she'll be able to find on fruit trees.
Also, how realistic would it be for her to have put kindling and wood in the tent the night before? She can survive in a post-apocalyptic America (defending herself, getting from Point A to Point B alive, finding and killing food) but I don't want her to have Locke-esque super-power survival skills.
We would gather pine needles and the small lower branches from pine trees that the large upper branches had kept dry. We would find pine trees with sticky sap oozing out and scrap the bark off. Then we'd make a platform out of whatever we could find (usually rocks but sometimes big logs) and make a tee-pee with the branches putting the bark and needles inside the tee-pee. Someone would stand over the tee-pee with their jacket protecting the wood and kindling from the rain. Then light it and wait for it to get strong enough that the rain doesn't put it out and add more wood as needed.