I hear ya RustyNails87. I hear ya. Had the same exact scenario happen to me last summer and managed to catch two little salmon and a 11.8 inch rainbow on nightcrawlers overall, but could never seem to 'match the hatch.' recently I bought a book that covers all the fly fishing insects in the Midwest. It lists over 80 mayfly identification pictures and the recommended flies to use with them. It also includes the caddisfly species, stoneflies, etc. The book is found here for $22 and I would strongly recommend buying it. https://www.amazon.com/Hatch-Guide-Upper-Midwest-Streams/dp/1571884815
Every mayfly I've come across has been in that book. To answer your question I would go the route of buying some clear bobbers
https://www.amazon.com/South-Bend-Slip-Float-4-Inch/dp/B003CUBANQ?ie=UTF8&keywords=bubble float&qid=1459122521&ref_=sr_1_1&s=sporting-goods&sr=1-1
and then once you can correctly identify the insects the fish are feeding on (you can scoop up some of them riding on the surface with a small minnow net attached to a long stick or pole), look up the flies that would match what your are seeing the fish taking, and finally buy them individually from Amazon, Orvis, etc. Make sure what you get can hold out for many beatings and can float for extended variations of time. Something like this:
https://www.amazon.com/Orvis-Real-Mccoy-Foam-Belly/dp/B006RBHTHS?ie=UTF8&keywords=real McCoy fly&qid=1462656869&ref_=sr_1_5&sr=8-5
For a setup, I'd try having the fly weightless, roughly 3-4 feet from your clear bobber and after you've casted, try and get separation of your fly from the bubble somehow. This is slightly different depending on if you're fishing dries, wets, streamers, or nymphs.
Try the advice given and if it works be sure to bump this thread to let us know how you do. if you have anymore questions feel free to let me know.
-UPSmallie