Here's a list I came up with awhile back when I was engineering all my ships after getting Horizons finally. This helped me remember what sort of things I was finding in each, so this might help you (or others) a bit. It's not totally 100% complete, but just the things I found in them when I started to document them:
Updated 8/10/17
DEGRADED
Systems: Anarchy, Low Security
Location: Everywhere
Info: Usually a ship has just been destroyed. Often has other ships there already, and contents are canisters of goods and such.
Materials:
May have data beacons (fly into the area closer)
Conductive Components
Mechanical Equipment
Chemical Processers
Galvanising Alloys
Heat Conduction Wiring
Heat Dispersion Plate
Hybrid Capacitors
Mechanical Scrap
Salvaged Alloys
Shield Emitters
Worn Shield Emitters
ENCODED
Systems: any
Location: Shipping lanes, but also outside of the lanes as well including deep space
Info: Contains usually data beacons you can scan
Materials: Common and Uncommon
Chemical Manipulators
Chemical Processors
Compound Shielding
Configurable Components
Electrochemical Arrays
Focus Crystals
Flawed Focus Crystals
Galvanising Alloys
Grid Resistors
Heat Conduction Wiring
High Density Composites
Hybrid Capacitors
Mechanical Equipment
Phase Alloys
Refined Focus Chrystals
Salvaged Alloys
Shield Emitters
Shielding Sensors
Worn Shield Emitters
Modified Embedded Firmware
HIGH GRADE (HGE)
Systems: High population (over 1 million), some say boom state is good, but outbreak, retreat is also good
Location: Deep Space or at least out of shipping lane, 100-1000ls from star
Info: These seem dependent on the system state as to what you get, but you find more in higher pop areas.
Materials: Rare
Core Dynamics (Fed and retreat)
Imperial Shielding (Empire systems)
Improvised Components (Civil Unrest systems, better with Independent and Refinery/Industry)
Military Grade/Military Super Capacitors (War or Civil War)
Pharmaceutical isolators (Outbreak)
Proprietary Composites (retreat)
Proto Heat Radiators
Proto Light Alloys
Proto Radiolic Alloys
COMBAT AFTERMATH
System: State: None, Retreat, War, Civil War,
GOVT: Any,
SECURITY: High
Location: Shipping lanes and normal space
Info: Left over
Materials:
Chemical Manipulator
Chemical Processors
Conductive Ceramics
Conductive Components
Configurable Components
Heat Conduction Wiring
Heat Exchangers
Heat Dispersion Plate
Heat Vanes
Mechanical Components
Mechanical Scrap
DISTRESS SIGNAL
Systems: Everywhere
Location: Everywhere
Info: Has Threat Level. Could be a ship being attacked or out of fuel.
Materials:
WEAPON FIRE
Systems: Everywhere
Location: Everywhere
Info: Has Threat Level. Has a rating from 0-4 of danger level (and how many ships). This is an attack, so you can pick a side or just loot
Materials:
Canisters, etc.
CEREMONIAL
Systems: Common in Tourism Systems
Location:
Info:
Materials:
CONVOY DISPERSAL
Systems: Everywhere (Common in Boom, Tourism)
Location: Everywhere
Info: Transport and Combat ships for scanning (or attacking if in an Anarchy system)
Materials:
ANOMALY
Systems: 130-150 Ly from Merope (Pleides Nebula)
Location:
Info:
Materials:
Unknown Artifacts (you can destroy for unknown fragements)