These were delicious and so simple! Split peas are really cheap, we mostly just wanted to test out how they would do as a flour. The only ingredients here are pea flour, water, salt and seasonings. It's not even leavened at all and it's still super tasty. Plus the color is just really novel and fun. I think it would be amusing to use this to make a zucchini or cucumber bread.
Peas seem to be less common as a flour than some other legumes, i.e. chickpeas, lentils, soy, etc. I figured maybe try looking for Indian recipes instead, since legume flours are more popular there, but even then peas seemed pretty under-represented compared to like urad, moong, etc.
Anyway, I dunno where you'd buy the flour itself, but if you've got a cheapy hand-crank grain mill these grind up pretty easy. 10/10, would reccomend.