Sure. I should mention before hand that I wouldn't expect my results to generalize to anyone else. I started tracking my diet when I began having health problems and distinct cognitive impairment. I imagine the majority of the benefit I've achieved from diet has been due to correcting things wrong rather than improving things right. That said, here's a brief overview:

Foods that rapidly bring on brain fog, degree dependent on quantity: Raw carrots, raw bell peppers, peanut butter, walnuts, pure sugar (even natural sources, such as sugarcane, but tentatively not honey), bananas, raw apples, enriched grains (tentatively, I've only tried this experiment half a dozen times), tofu.

Whether the food is cooked or not seems to matter, but I've only experimented with this for a handful of foods.

Among the foods I do eat I prefer those that provide an even level of energy over time, to avoid crashes: lean protein, oats, olive oil, non-starchy vegetables; however, there are foods/drinks that provide positive cognitive benefit in the short run, such as: some alcoholic drinks, starchy vegetables (yams, sweet potatoes), coffee, mint tea.

For the sake of simplicity in analysis I almost always restrict my meals to 4-5 ingredients, and almost never eat out.