FYI: You can get Ancient Seeds in the Sewer (Spoilers) : r/StardewValley
Undeath and The New Winking Skeever Patch at Skyrim Special Edition Nexus - Mods and Community
Bathroom New Floor Drain Deodorizer Sewer Deodorizer Cover - Temu
This feels like a bug. Archaeological site under a city that was founded a long while before revealing archaeological sites. I indeed was able to get an artifact from it. First time