I'm embarrassed to admit I read and loved these but:
The Area 51 series by Bob Meyer (originally published under the pen name of Robert Doherty) is on sale.
$0.99 a book at Amazon US.
The series starts as military fiction dealing with Area 51. But as it goes on, Bob throws in every bit of kooky lore that he can fit. By the end you have read about aliens, pyramids, Merlin and Excalibur, Nosferatu, bigfoot, Sir Richard Burton and more that I can't remember.
It's schlock. But it's entertaining schlock. The series went through nine books (originally published by Dell in the '90's), then there was a spinoff (The Nightstalkers) and a spinoff of the spinoff (Time Patrol) and now it looks like he's continuing the series. But really, if you read the first seven books (ending at The Truth), the story ends there.