I want to include fruit trees in my garden beds, specifically apple. Any suggestions on what to plant underneath apple trees because I do not have space to just plant trees and I want to incorporate the trees in with my perennial/shrub/annual beds.
I would suggest annuals and perennials should be ok at the close basal area ( try to keep them 10 to 12 inches away from the trunk) and small shrubs more like 24 to 36 inches from the base. Trees need their water and nutrients too, putting lots of other plants in the soil to compete with them for those commodities can be tough on the tree.
Sedum ternatum is a native of the eastern U.S. and would be a great choice under a tree. It thrives in shade and would help to hold the soil in place.
Use among evergreen shrubs as focal points, same as flowering crabapples and other ornamental trees. Heavy pruning is not required. You do still have to be able to get at the fruit, of course - you are going through the bother of working among the shrubs at harvest time in order to have the pleasant visual effect the rest of the year. See Grant, Garden Design Illustrated (Timber) for photo and discussion.