Books and journals of potential interest are available in three Penn Libraries locations: the Penn Museum Library is Penn's library for anthropology and archaeology, the Fisher Fine Arts Library houses materials related to landscape architecture and garden design, and Van Pelt Library is Penn's general library for humanities, social sciences, and general sciences.
CC79.5 .P5 for Archaeology: Methodology: Plant remains and pollen
CC81: Environmental archaeology
E98 .A3: Native North Americans: Agriculture
E98 .B7: Native North Americans: Ethnobotany
GF: Human ecology
GN476.7: Ethnobotany
GN700-799: Prehistoric cultures, especially GN799 .F6 on prehistoric foodways
GT2850-2920: Food and drink customs
QE900: Paleobotany
QH: Natural history
QK: Botany
S: Agriculture
SB: Plant culture
TX341-641: Nutrition
TX642-840: Cooking
Fruit or Fruit trees
Gardens (look for something more specific like "Kitchen gardens" or "Gardens -- Italy")