俺们那嘎山上有真蘑 - is this really what it says, and if so why?

Question

Following on from my question about the song 东北人都是或雷锋, I noticed one of the lines seemed to stand out a little.

In the song, 老张 has invited the 东北人 who rescued him from a vehicle accident to dinner. The drink flows freely, and his guest holds forth about the character of the local people:

俺们那嘎都是东北人,    Around here we're Northeasterners
俺们那嘎特产高丽参,    Around here our specialty is Ginseng
俺们那嘎猪肉炖粉条,    Around here our dish is braised pork
俺们那嘎都是活雷锋.    Around here we're all living Lei Feng's.
俺们那嘎没有这种人,    Around here we don't have people like that
撞了车哪能不救人,      If you're in an accident how can you not help
俺们那嘎山上有真蘑,    Around here there are Hazel mushrooms in the mountains
这个人他不是东北人.    That guy is not a Northeasterner.

The second to last line above seems out of place. He's talking about how 东北人 are the sort of people who will help someone in trouble, and contrasting it with the caddish behaviour of the driver who caused the accident and ran off: clearly not a 东北人. So why is there this odd line about 榛蘑 (hazel mushrooms)? Is it just there as a filler?

Listening to the song it doesn't sound like that is actually what he is saying and I'm not the only one to wonder about that line. This post on Baidu asks:

东北人都是活雷锋里面那句“俺们那旮答山上有真蘑”啥意思?

and someone answers:

原话是：俺们内噶身上有正根 你觉得这句词要是不处理一下，能发行吗，全国老少谁能答应

(The original said: 身上有正根. Do you feel this could be published if they didn't change it, nobody would agree to it otherwise!)

I sort of feel I have an idea what it could be getting at, but searching on that term only returned mathematical definitions such as "positive root".

Can anyone clarify please.

Answer 1

"榛蘑是中国东北特有的山珍之一，和肉蘑一样，也是极少数不能人工培育的食用菌之一。

• "不能人工培育" means "it is not possible to reproduce manually", which hints it is "a true, rare nature product".

The interpretation of the lyric, therefore, is - "俺们那嘎山上有(如假包換的)真雷锋/(榛蘑)".