The following are mottes (allegedly) and are examples of mounds all around the UK that originally got me started thinking along this particular line.

http://www.discovernorthernireland.com/accomfinder/product.aspx?ProductID=3171

now does that one look spookily familiar?

http://images.search.yahoo.com/images/view?back=http%3A%2F%2Fimages.search.yahoo.com%2Fsearch%2Fimages%3Fp%3Dmotte%2Band%2Bbailey%2Bcastles%26js%3D1%26ni%3D21%26ei%3Dutf-8%26y%3DSearch%26fr%3Dytff1-msgr%26xargs%3D0%26pstart%3D1%26b%3D43&w=473&h=239&imgurl=www.ballybegvillage.com%2Fimages%2Fknockgraffon_motte_baily.jpg&rurl=http%3A%2F%2Fwww.ballybegvillage.com%2Ftower_houses.html&size=16.5kB&name=knockgraffon_motte_baily.jpg&p=motte+and+bailey+castles&type=JPG&oid=8f86f102c59b9c58&no=47&tt=282&sigr=11geqdbnt&sigi=11rjq7d81&sigb=148ef0ccq

Another one in Ireland.

http://www.castleuk.net/castle_lists_midlands/164/oxfordcastle.htm

you need to scroll to the bottom for the motte pic

http://en.wikipedia.org/wiki/Barnstaple_Castle

Although they all are claimed to have been purpose built by the castle builders, I doubt much evidence is extant - core samples, excavations etc.
as only outermost layers are of much interest to archaeo's who actually have excavated mottes, as they will usually have assumed the date of the mound to be contemporary with the earliest castle building phase only.