Mine have been the sawtooth oak for acorn producers, keiffer pear (transcendent or dolgo crab #2)as a fruit trees, and elderberry and button bush as shrubs. I'm sure there will be many different answers depending on everyone's zone and soils. I do maintain my trees, by the way. These are just some that have still flourished even if I accidentally forgot them a year. Name as many plants as you like as long as they meet the criteria. Go!