Well, often times the best Benches are made from wood, so we're going to need some logs for that. To make Logs, we need a Level 5 Tree. To make a Level 5 Tree, the starting point is of course Seeds Level 1.

 

Once you have a level 4 or above Logs item, simply tap to create a Bench. You can merge Logs to a higher level to create higher level Benches.