Yes, you can pick berries and mushrooms in a forest without any restrictions. I remember when I went fishing in the late 90s to Oka river in the rural area in Vladimir region about 400 km from Moscow I was approached by an old lady who suggested to bick a 10 liter BUCKET (!!!) of blueberries for me for only $2 (!!!). She did that but I was too embaressed to pay such insignificant money and gave her $10 (I haven't much money myself back then). She was very grateful and said "thank you" endless times. I went to the same area last year and the price among locals to pick a bucket of blueberries was about $100 because many rich Muscovites built dachas there (the nature there is very beautiful) and locals who hadn't any work 10 years ago because kolkhoz there they used to work in Soviet times was completly ruined during the times of "freedom and democracy", work now building those houses, many opened their own buisnesses providing various services to those dachniks and earning quite decent money. Also pensions of the old people became significantly higher for the last 10 years and they are able to live on them now instead of begging how it was 10 years ago.