Our Z.Chief recommends you use our treasure hunters to collect sign sets and exchange them for quartz. There is a little trick: treasure hunters get more road signs if you have different plants on the island.
It seems Boneberry gives the most complete sets. Need more Picnic Site signs? Plant Purple Hands, Peas, Pumpkins, or Tomatoes. Need No Entry signs? Plant Sleepgrass or Currants. Need One Way Traffic signs? Plant Blueberries, Cactus, Chili Peppers, or Sunflowers. Need No Overtaking signs? Plant Black Hands or Boneberry. Need Road Works signs? Plant Poppies, Sleepgrass, or Sundew.
It seems Boneberry gives the most complete sets. Need more Picnic Site signs? Plant Purple Hands, Peas, Pumpkins, or Tomatoes. Need No Entry signs? Plant Sleepgrass or Currants. Need One Way Traffic signs? Plant Blueberries, Cactus, Chili Peppers, or Sunflowers. Need No Overtaking signs? Plant Black Hands or Boneberry. Need Road Works signs? Plant Poppies, Sleepgrass, or Sundew.