It's fairly common for people to not remember their dreams. It's widely accepted that everyone dreams every night, multiple times, but not everyone remembers them. Having good dream recall is a skill that takes practice, and keeping a dream journal is the most important thing you can do to build that skill.
In the morning when you wake up, just try to lay still and remember something, anything that happened during your sleep. Even if it's just one word at first, write it down, every day (a note app on your phone is a good place to start.) Over time if you do this consistently, your recall should improve. Laying still, and moving slowly when you wake up is also very important to recall, because once you start to get up your brain fires off all kinds of stuff to get you going for the day and erases your dream memory.
If you want to try something that should work for most people to increase dream vividness and give you a higher likelihood of remembering your dreams, buy vitamin b6 tablets. Vitamin b6 is required to convert the amino acid tryptophan into serotonin, which should increase dream vividness and recall. I would suggest taking 100mg along with 1-2oz of cheese(source of tryptophan) maybe 1 hour before bed. You could also purchase a 5HTP supplement and take 100mg of that alongside the b6 instead of eating food, which would most likely produce stronger results.
Cannabis and alcohol use typically reduces people's dream recall. As for mugwort you should be able to find some, but speaking for myself personally I didn't notice any effect from consuming it other than a slight allergy. It can be made into a little "pillow" in a small bag and placed under your pillow to induce prophetic dreams. Pretty sure that's in many European folk traditions as well as some neopagan/wiccan traditions.
