I've found a castor oil based repellent (Dr. T's Mole Out @ Lowes). It's 10% castor oil mixed with 90% clay pelletized. Now, the label says safe for yards, flower beds, gardens, etc. but it doesn't say VEGETABLE gardens specifically. Paraphrasing, the directions say poke a hole in the tunnel every five feet and pour a tablespoon of the granules in.