Answer: How frustrating! Going by your description, I would suspect woodchuck and/or deer, especially on the asparagus tops. You might try watching in the evenings and early in the morning to solve the mystery. In both cases, a fence is the most reliable long term deterrent. Woodchucks can be unpredictable and their bites are terrible so if that turns out to be the culprit you might want to have it professionally trapped and removed for safety's sake.
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