Sculptor Anna Gillespie lives and works in Bath where she infuses her figurative sculptures with elements collected from nature including numerous acorn caps or beechnut casings. Gillespie also works with bronze and stone, often recreating some of the same environmental elements by hand, a process I imagine is even more meticulous than harvesting and using individual seeds themselves. She most recently had a solo show at Beaux Arts Bath and you can follow her more on Facebook. Gillespie also published a book of her work spanning 2006-2012 where you can see many more stunning images of her sculpture. (via my modern met).