Within fishing's general spectrum, fly fishing is a shallow water, finesse tactic. Imagine the back of a cove during Spring. In the clear shallows bass guard nests around a fallen tree. A search lure, like a crankbait, is out of the question, jig and plastic might work, or a live bait rig, but both involve a loud "plop" right on top of nervous fish. If only you didn't need weight to deliver your bait. Fly fishing does this and the excitement of such situations "hooks" anglers on the method. Trout in small spring creeks, panfish in the shallows, carp browsing a gravel bar in a small, clear river, a smallmouth bass tucked behind a rock nearby are a few Iowa fly situations.
There are limitations, however. Deeper than 5 feet you're pretty much wasting time, the same goes for "searching" or "covering" large areas of water with fly gear. Fish must see the fly, scent and vibration are not part of the presentation. And there is back casting space to consider, or is there? You see, it's a method with simple origins, deep traditions, but a modern explosion of complicated, tactic specific gear. Fortunately we now have video files online where at a glance you'll see various types of outfits and the applicable environment and casting mechanics.
An all around starter outfit in Iowa would be an 8-9 ft. 5 wt. If trout streams are your main interest, consider a shorter, lighter 3 wt.outfit. If you fish from shore around dams or other high bank areas you might need a micro Skagit head like the OPST Commando in dealing with limited backcasting space. Planning a backpack trip to the mountains then lightweight tenkara is the ticket, but if you're visiting coastal, or Great Lakes salmon/steelhead rivers then long-range Spey or mid range Switch outfits might be called for in either their traditional, Scandinavian, or Skagit manifestations.
Setting aside these specialty applications, let's return to that basic 8-9 ft. 5wt. outfit. Along with the rod you'll need a reel and 4 kinds of line (yes 4 kinds of line, backing, fly line, leader, and tippet). Don't spend too much on your first rod and reel - you'll still need to watch casting videos and practice no matter what rod you buy and outside of large, long-running fish like carp the reel does little more than hold line. Save your money for a quality fly line. For starters a WF-5-F.
WF, weight forward, describes the distribution of casting mass.
5 weight, describes the amount of mass in the first 30 ft. of the fly line.
F, floating, indicates additives in the plastic matrix making the line float, hover, or sink.
Fly line cores vary from soft, supple trout cores for easy line management in cold conditions to stiff bass, pike and saltwater cores for distance with large flies in hot weather, but a good multipurpose line can cover both ends of that spectrum. A 3x tapered leader might be a general starting point, but I recommend tying 5 ft. of 20# monofilament to the front taper of the fly line, then 4 ft. of 8-10# fluorocarbon monofilament to the 20#. Knot tying instructions are found in or about the fly line box or online. If the situation calls for a lighter, more delicate presentation add a few feet of 6, 4 or even 2# tippet, or if fishing for pike add a wire tippet. Constructing your own leader in this way allows customization for windy, muddy conditions or calm, clear conditions. Pinch the leader with a piece of leather and by stroking create a little frictional heat removing memory coils. Now you're ready for a fly on the end of your tippet.
A size 8 beadhead Woolly Bugger could catch a great variety of species; trout, panfish, bass, carp etc. Add a basic nymph or 2 (aquatic insect larva), and a general dry or 2 (aquatic insect adult) on the small end of the scale and a baitfish imitation (perhaps the venerable Clouser Minnow) on the large end and you're ready. Of course, you'll soon want more specific flies and eventually begin creating your own, but for now practice casting and tying knots.