Harvest Moon: A Wonderful Life Special Edition

Despite the initial reading of the description, you might want to get a pool of money (1,000g) and save before trying. Now, you'd think that, over the course of the game, you'd have 20 crops planted, right? But unfortunately, this will actually require you to have twenty crops planted at one time. This could be over the course of a season, but the real focus is to make sure that you try hard for this. The reason I suggested saving is, if you're wanting to get this out of the way, just buy the lowest crop for the season which may either be the Tomato or Turnip crop and plant all twenty of them right then and there.

20 Turnips will run you 400g. 20 Tomatoes will run you 600g. Either way, save, buy 20, plant them all among your poor or decent soil, get the trophy, and reload. It'll save you struggling to satisfy this normally early on.