You're right. The skin of grapes, wine and even peanuts (peanut butter) and mulberries have resveratrol.
Having said that, there just isn't enough in foods to get the specific effect you're after. It's been a while since I've looked but if I remember correctly, the content in wine is something like 10 mg/L, so short of being a chronic alcoholic, you won't be getting enough.
To get an effect where one would antagonize estrogen receptors and increase gonadotropins would require eating astronomical amounts.
Now, that isn't to say that one still can't reap other benefits from resveratrol independent of ER-antagonism at much lower intake levels. In fact, some authors have argued that resveratrol may be the greatest explanation for the "French Paradox." So, even smaller amounts that one obtains from foods is likely highly beneficial.