Mugwort: Artemesia vulgaris
Mugwort is an old-time remedy, used for everything from insect repellent to protection agains wild beasts, it replaced hops for making beer and was stuffed in shoes to avoid tired feet. It is still used to this day ritual purifications, and to enhance dream states. In fact, stuffed into a pillow it was said to reveal the sleeper's future to him or her in a dream.
While I can't attest to my future being revealed to me in a dream (only time will tell, I suppose), I can tell you that the leaves, even just placed by the bed or under a pillow, can have profound effect on dreams, making them vivid, memorable and sometimes bizarre. Named after the goddess of the moon, Artemis, it is said to gain in strength with the lunar phases, being most powerful at the full moon.
"Mugwort is a sacred plant medicine who brings us into contact with the otherworld. Mugwort presents a portal wherein we are invited to perceive messages from the spirit realm, connection to our ancestors, gallivants with our shadow selves, and windows into the twinkling depths of the unseen." -Rachel Blodgett
Mugwort is mildly euphoric, anti-spasmodic, and helps to calm nervousness and even insomnia. It has emmenagogic properties, and thus should be avoided in pregnancy. It brings on sweating, and can help break a fever during colds and flus. I use mugwort in my Herbal Dream Eye Pillows to help enhance the dream state as well as help with dream recollection.
Ceremonially, we will be burning mugwort smudge in ritual purification, and a flower essence and/or tincture will be offered but not necessarily ingested.