In June I will be removing the organic layer in the area my cabin will sit. Is this material good to keep to use in my garden? I have been told that many people get rid of it but I wonder if it is useful. My concern is that the trees are all pine so I wonder about the ability to grow in it. I will be building a greenhouse and would be able to mix other material with it if I need to.
A simple PH test would help you determine that. Also, call your local extension service and discuss it with them.
most likely it is acidic (evergreens love acidic soil) and will require a bit of lime to neutralize for gardening...as bkmail mentioned, ph test it. The ph should neutralize somewhat after normal composting with other household ingredients (fruit/vegtable peelings, egg shells, shellfish waste, coffee grounds, tea bags, etc.).