You can plant roses that you're given as gifts. Willow creek has a couple of wild rose plants you can get for free.
Wild fruits and vegies are a good way of starting up your garden. Foraging can get you plants like onion, strawberries and potatoes which are good as cooking ingredients. Once again, Willow Creek has wild spawns for these plants.
Evolve as frequently as you can, and plant out evolved produce. When you get grafting, go nuts with multi-species hybrids. An apple, lemon, pomegranate tree saves a lot of ground space!
Use your excess Parsley as fertiliser.
Carl's guide to plant locations :
https://carls-sims-4-guide.com/skills/gardening/plant-locations.php
