They like to mow...and in straight lines, dagnabbit.

tj

Lawns are most effective in large sweeps. Keeping grass and planting well separated makes upkeep easier. And grasses and other plants, including trees are adversaries, the grass even using herbicidal exudates (as do some trees and shrubs) to suppress the other plants and take over. Small, recently planted lawn trees need a wide circle of mulched bed to keep the grass from interfering with them. After many years, when the trees are large or when putting lawn beneath high-branched existing trees the grass should be brought right up to the trunk for the most gracious effect. Otherwise, a small grass-free area around a tree trunk is liable to look like a socket - or worse.

Small-growing or shrubby trees planted near foundation aren't likely to cause adverse impacts to the structure. An informal bed layout may rather often have a situation that calls for a tree accenting the wide part of a bed where the backdrop is a house wall.