I almost forgot, and I don't know if most of you would consider this a crop, but Mahogany is one of my favorites. Some day soon I will detail and explain proper forestry practices and viability, but Mahogany farming can cover so many different facets of the game. The most obvious is hardwood, but with the wood chipper you will not need to go harvesting normal trees for wood very often, and then there's of course the charcoal kiln as well. On top of this, each Mahogany seed will sell for 100g each, which you will get from chopping, shaking, or just harvesting off the ground, not to mention how much you can earn if you sell excess amounts of wood/hardwood. And by the nature of tree farming, I prefer to have TONS of grass, so as to not overwhelm myself with the task of managing too many trees at once, which makes ranching various animals a good secondary source of income. Usually coop animals, as they require less maintenance, but I do also keep at least one barn for utility and diversity, even if I don't retrieve their products daily.
Anyways, tree farming is very viable, and even before you get mahogany the other tree's nuts sell for a small sum, I think acorns being the most profitable at 20g a pop