https://www.google.com/maps/@43.221692,-122.7898361,242948m/...
TL;DR: Railroad developers were granted alternating square mile sections as a reward for their investment.
Key things to worry about: try to avoid placing spiky and poisonous plants where people walk, or highly invasive root systems like figs near pipes and building substructures. Try to pick species that self-limit to a rational height, you don't want to have to hire people to prune your garden when it decides to fall on your house, infrastructure or members of the public. Otherwise just go for it. Don't get discouraged if stuff dies, that's normal.
Thrift methods: Guerilla gardening on public or disused land. Seed and spore can be readily collected and germinated. Plants can often be divided. You can use an outdoor area as a germination zone by adding extra moisture and controlling maximum sunlight exposure. You can go vertical with climbers, many of which have excellent flowers and do not need much earth. If you have a raised balcony or cantilevered deck, you can let plants flow down the exterior, a technique long popular in Vietnam.
If you have particularly bad soil you can grow in pots or learn to graft rootstock, but this is tedious and expensive relative to the alternative of direct sewing and will not result so easily in an integrated ecosystem.
Personal top botanically inspiring places in the US: Brooklyn Botanic Garden, Chicago's Lincoln Conservatory, Missouri Botanic Garden.
my dream is that their lunch is eaten by oss