This is super interesting! 
I hope you don’t mind, but I thought this was such a great topic to explore that I pulled it out of the recipe comments and into a thread all its own. I didn’t want it to get buried in the replies!
This is the first I’ve heard about dandelions attracting spirits and shadows- I have always considered and used them as an element of the sun 
. But I suppose it is thanks to the sunlight that there are shadows, yes? 
I’d love to learn more about the “darker aspects” of dandelions!
Lilacs, however, I have heard about their darker side: attracting spirits and bad luck. Here in Poland, there is a folk legend that if you take a replant a lilac tree, someone in your family will soon die. My partner says its true 
It’s tricky, because when I look online, information about lilacs seems mixed and even contradictory- the Learn Religions article about Lilac Magick and Folklore says:
The purple and red varieties are usually less feared, but even they are sometimes excluded from house-decorations as bringers of misfortune…
But then later in the article they say:
Plant lilacs around your property to keep out those who might do you harm, or cut some to keep indoors as a way of preventing malevolent spirits, or other ghosts and haunts, from hanging around.
A bit confusing- I guess lilacs are one of those things where you should use your own personal judgment and experiences to determine its uses in magick. For some, it may be a protective barrier, like wisteria, while for others it may be used to attract and draw spirits in the same way that heather is.
Purple/blue flowers sure have a lot of interesting uses in magick! 
