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The symbol, though defaced, is probably the symbol of the Hitlerjugend. Click the link to see the actual image, I don't want to post it here, since it would be a legal grey area for me to do so for reasons also explained in the wikipedia page.
The L.D. and H.J. probably stand for "Landdienst" and "Hitlerjugend". Landdienst was a branch or troop of the HJ educating young boys over years to become farmers. So this likely was a farm house in use with them, probably in a part of Poland that was either Germany back in the day, or a part of Poland that Germany considered their core territory instead of "occupied".