Possible Clues:

• Caterpillars, maybe
• Strong drawers
• Vehicles for heavy farm work
• Vehicles at some monster truck rallies
• They are often taken on field trips
• Some Caterpillars
• Cultivation wheels
• Thesis or last pamphlets? They have some pull and draw for the farming community!
• Signs of spring
• Short test for players breaking new ground across the turf