It is easy enough to overlook at the start of the game, but as you play through Story of Seasons: Friends of Mineral Town you are going to find that you need a lot of lumber and material stone. Every upgrade to your houses, or farm buildings, will need a lot of it. It is much easier to just grab a little bit every day and let it all build up than it is to suddenly realize you need hundreds of pieces of each one.
The main way you will get both at the start of the game is by breaking sticks and stones on the ground. You can break wood with an ax to get lumber, and you can break rocks with a hammer to get material stone. After collecting your lumber and stone, you can store them in your cabinet in your house.
You can also find large boulders, and tree trunks, as you wander around your farm and the surrounding area. These all come at different levels, from 1 to 5, and you will need tools that match or exceed those levels to break them. Doing so will get you far more lumber or stone than you will get from breaking smaller rocks and sticks. If you want to learn more about upgrading your tools, you can read our tool leveling and upgrading guide.
The good news is that various rocks and tree trunks will randomly spawn each day, so you can happily clear them all out and more will return the following morning.
On the map above we have marked the various spots that the tree trunks and boulders can spawn. You should check a couple of these spots each day, especially after you level up your ax and hammer to Silver and Gold levels, and you will quickly start stacking up a good stockpile of both materials.