Caffeine is great. I love it. It makes me happy. It also comes from unethical plantations in faraway places and leaves a huge carbon footprint. Luckily, there are a number of options for growing at least some at home, reducing dependence on the global supply chain for coffee and tea. Best results in warmer, wetter climates, but these aren't impossible if you live up north.

Coffee - To my understanding, the berries, beans, and leaves are all usable. Raw beans can be roasted to your preference in an oven

Tea - Leaves can be brewed fresh or dried

Ilex Spp - Various plants in the Ilex species contain caffeine, including Ilex Vomitoria, or Yaupon Holly the only caffeine-producing plant native to North America (does not make you vomit). This genus also includes Yerba Mate and other caffeine-producing holly shrubs

Those looking to grow caffeine in their garden may also want to look into Ephedrine-producing plants as well, including various plants in the Ephedra genus and Sida cordifola, a Florida native plant