There was an old lady--- yes, there was! Her entire yard was solid dandelions. She harvested the flowers to make wine and the greens for a vegetable. The wine was an acquired taste as well. This was back in the 1930s, and no one objected to the dandelions. Now the pure lawn society would have her up for violating bylaws against weeds. I have seen the occasional article praising the dandelion; mayhaps its time will come again.
Sassafras trees were uncommon where I was raised, so never heard of them being invasive. We have a weak tree here called the Manitoba maple which seeds all over the place; along with the chokecherry it tends to be "invasive."