Is patches a proper noun

No, the compound noun pumpkin patch is a common noun, a Word for any pumpkin patch anywhere.

A proper noun is the name of a specific person, place, thing, or a title; for example:

• The Pumpkin Patch Preschool, Hackettstown, NJ
• The Great Pumpkin Patch (entertainment venue), Hayden, AL
• Tim's Pumpkin Patch (pick your own pumpkin), Marietta, NY
• Door County Pumpkin Patch Festival 2012, Egg Harbor, WI