ground a single barbed shaft 78 completes pin 70 pin 72 in fig9 can made from biodegradable material such as biodegradable cornstarch or the like pin 72 has a pair of barbed legs 80 and 82 a head 84 has metallic coating 86 applied thereto coating 86 can contain iron oxide iron filings or other metal metal oxide material that is attracted to a magnet of the magnetic pucks other techniques for making plastic pins have u201c magnetic u201d heads for being picked up by the magnetic pucks will be readily apparent to those skilled in the art based on the disclosure set forth herein another prevalent pin for attaching waterway matting to the ground are elongate staples such as staple 88 in fig1 by altering the design of the magnetic puck the inventive insertion units can pick up staples and insert them into the ground an insertion device 90 is formed like the device in fig6 including the magnetic puck in this staple embodiment however a pair of spaced apart non magnetic shims e g aluminum or stainless steel 92 and 94 have been affixed to the lower bearing ring 66 to leave a valley having a width only slightly wider than the width of the head of staple 88 the depth of the valley is greater than the height of the head of staple 88 staple 88 now will be easily and firmly retained in the formed valley shims 92 and 94 can be the same thickness but preferably one of them will be slightly thicker than the other one in order to enhance the urging of staple 88 into the valley formed therebetween yet another unique pin.