Anyone else notice that the giant metal heads near police stations and other buildings are VERY similar to the TES dwarven head statues?

Looking very close at the heads in Fallout you see lots of PIPES and VALVES!!!!

Is there any firm lore connecting TES world and Fallout world?

Or just easter eggs, like the road signs in Fallout 3 that said TES IV or something like that.

It is just art flavour. A lot of the Gotham City or Top Ten graphic novel art has similar city heads like that. Yes you are correct in your observation about the "Unknown Plant" but it makes no singing noise.

The metal heads on buildings have been part of the series since Fallout 1:

http://hydra-media.cursecdn.com/fallout.gamepedia.com/6/62/Fo1_Hub_Bad_Ending.png

http://hydra-media.cursecdn.com/fallout.gamepedia.com/a/a3/Fo1_Necropolis_Bad_Ending.png

So Doctor Who, Star Trek, and The Hitchhiker's Guide to the Galaxy take place in the same universe as Fallout?

Well you can also find an iron helmet from skyrim in wolfenstein the old blood. And i don't think super nazis fit into either series. Bethesda just really loves easter eggs.

Well, with magical weapons now being in fallout 4 I wouldn't be surprised...

Do you know that the fallout series was not created by Bethesda, right?

No, the lore isn't even close to compatible. For one, FO takes place on Earth which has distinct geography from TES's Nirn. Additionally, the Deadric Princes would be known in Fallout if they existed, as those beings are tied into how the universe functions and they can not be destroyed. The Princes also all have egos that would not allow themselves to be unknown. There are no known instances of Observer, King, Rebel (Enantiomorph). And more things along this line.

Tamriel is actually Thundera in the far future, and Fallout takes place in the distant past of the Care Bears universe. Also, Marc Singer is The Beastmaster AND Mike Donovan at the same time.