Command:

curl -s https://inventory.firebaseio.com/items.json|jq '.[]|select(.box=="Clamps")'

Output:

{
  "box": "Clamps",
  "container": "Bin 1",
  "item": "Small Clamps",
  "loc": "Rack",
  "qty": "4",
  "worth": "0"
}
{
  "box": "Clamps",
  "container": "Bin 1",
  "item": "Med Clamps",
  "loc": "Rack",
  "qty": "4",
  "worth": "0"
}
{
  "box": "Clamps",
  "container": "Bin 1",
  "item": "Corner Clamp",
  "loc": "Rack",
  "qty": "1",
  "worth": "0"
}

Command:

curl -s https://inventory.firebaseio.com/items.json|jq '.[]|select(contains({item:"Clamps"}))'

Output:

{
  "box": "Clamps",
  "container": "Bin 1",
  "item": "Small Clamps",
  "loc": "Rack",
  "qty": "4",
  "worth": "0"
}
{
  "box": "Clamps",
  "container": "Bin 1",
  "item": "Med Clamps",
  "loc": "Rack",
  "qty": "4",
  "worth": "0"
}