The Mountain Project notes that there are two glacial erratic boulders in the Landlocked Forest that make for good bouldering practice.
They have a map to find the two boulders and all sorts of other nifty information.
Here is their description: This area is typically used for mountain biking and dog walkers, but there are two glacial erratics that lie on the far side of Bannon Hill. Foundation Boulder has some decent routes that range in difficulty with a 10 foot topout. Bannon Hill Boulder is shorter, about 6 feet high, but had many good holds for a quick warm-up, but it needs to be cleaned.