Cut the bottom off a plastic pot to contain invasive plants & bury in the ground. I have been doing this for a few years & works great for containing plants that tend to spread, but that I still want to plant in the garden. This also works good for planting a plant in an area that tends to get filled with roots etc. from other plants. I will use a larger pot so that the plant can spread it's roots and grow deeper roots, but keeps other tree roots from choking out the one I planted.
Astilbe : this perennial is a great shade plant with dense foliage + feathery, summer blooms for a shade garden. aka False Spirea, False Goat's Beard. Astilbe is native to Asia and North America. Blooms in June-July. Colors include pink, red, white, purple and peach. Plants grow 18" to as much as 5 feet. There is a dwarf variety that grows about 6". Pairs well with hydrangeas, hostas, & ferns.
Cardinal or Cypress Vine. Ipomoea quamoclit. plant it once and you have it for a lifetime- it grows like a weed in Texas. If it goes where you don't want it, it is fairly easy to pull off. I love the vivid red against the brilliant green. Hummingbirds love it.