Before you get any crops growing, buildings built or, well, anything else, you're going to need to clear the absolute mess that is your fields.
You'll find logs, stone, weeds and a variety of other things clogging up the fields. You'll need the scythe to make quick work of small plants and grass, while logs and trees need the axe.
Stones can be broken apart with the pickaxe. Meanwhile, larger stones and logs will require you upgrade your tools, so that's a job for later.