This is a pre-1840 event. If you don't have a decent hat, make a bandanna. A good bandanna is nothing more that a piece of cloth 3 feet square. You don't even have to hem it. This is the toughest thing for a beginner to get without spending a good bit of time making moccasins or spending some hard cash, unless you go barefoot.
Fields are full of stickers and prickly pear.
You've been warned. Mocs are the best, whether they're Dyers or homemade. I've seen few from Tandy that will hold up to a week at rendezvous, but many people start with these. Rubber soled mocs are a no-no, but if you're a newbie, and keep both feet on the ground all the time, most folks won't say anything to you. Cowboy boots are definitely out.