As that link says about one of those mounds -
"Oval barrow 750m N of Wallis Grange. Identified as a Neolithic oval barrow, the only securely identified example in Humberside. The mound survives up to a height of 1.75m and measures 52m long E-W by 30m wide N-S"
That's news to me, it's got me licking my lips and checking the weather forecast...
-Chris