I'm heading up to the Grand Canyon tomorrow for a couple days of painting. My supplies are always changing, but here is what I'm using right now:
(Clockwise, from top left) French easel, canvas brush roll, flat bristle brushes from size 2-10, palette knife, oil paints in a protective plastic box, two wet panel carriers (8x10 and 9x12), plastic grocery bags, viewfinder, flashlight, micron pen (for writing on the back of panels), pencil, wooden palette, paper towels, brush cleaning tanks, backpack.
Not pictured: Big hat and a travel blanket. These are able to fit in the backpack as well.