I tried to visit the barrows today and found the site very overgrown (mostly with holly) and access was very difficult to the point where I left without getting a look at the barrows.
The footpath from the road runs next to Grim's Ditch which can be seen where the undergrowth (or overgrowth!) is less dense but the barrows are on private land and I didn't want to spend too much time battling through the bushes.
I've visited the two 'barrows' in Oaken grove wood in 1996 to find:
There is a small layby to park. Follow the footpath into the wood.
The first barrow which I called the west barrow is shrouded in bushes however the ditch is still visable. On my visits the ditch of this barrow was water logged.
The ditch is broken by two causeways opposite each other .
The summit of this squat mound has a deppression in the centre. Suggesting it may have had excavations in the past. The record of Buck suggests it was done in Tudor times.
The second barrow at the east is much more impressive looking very similar to a Norman motte. It has a shallow ditch with the same two causeways. The summit has been dug out to a deeper level.
Intresting point is that small pieces of red tile are scattered down the side of the mound, some can be seen in the ditch. A building with a tiled roof presumably existed on top of the mound. The records of Bucks records that the mounds are Saxon Block houses to defend against the danish threat.
The earthwork of Grim's Ditch passes a few feet south of both mounds. A third mound exists west in the field across the road. In the grounds of Hampden House.