@Bonsai Nut - walnuts - I suppose one could style them like Kimura styled the Japanese native sumac he displayed on occasion. Each trunk a single line with a palm tree like whorl of compounds leaves at the top. In autumn color the sumac (genus Rhus) have beautiful autumn color. Sadly the autumn color of walnut is basically yellow with brown blotches. Not very attractive.
Find a spot in the yard to plant the walnuts in the ground, let them grow. At 30 to 40 years they will be worth thousands to a lumber mill. Walnut for veneer and furniture making is always in demand. Your grandkids could make bank on walnuts planted now.
In the Chicago area there is a lumber yard that specialized in specialty wood harvested from street trees and urban landscape projects.