Thank you very much for your answers. Now I'm confident that is one of the first two from Dave sugestion list. It seems to be even edible.
How can I see the spor print color, how should I proceed?
Unfortunately now I am in Germany and going only in holydays to Romania. Next time when I will go I will make some notes about my finds.
The place where I grow up is in the South-East of the country, near to the Danube river. The forest here is mostly soft wood (Willow, Aspen) and sometimes Pine forest. Usually in the spring and autumn many species from Agaricus family are growing. On the dead logs especialy in the autumn Pleurotus ostreatus and Panus Tigrinus are to be found (the second one grows from Spring to Autumn). Polyporus squamous is also present on dead logs and is quite delicious.
Further to the North , in the Carpatian forest they are much more species to be found. There are peoples in that region that are living only from mushrooms harvesting. This is like a way of life. For a mushrom hunter may be a nice place to visit, if you're not affraid of bears.
Daniel.