你是法律专家吗？冒充的吧？我不是法律专家但是我可以告诉你你说的不全对。

公园是私人和国家所有没有错，不能私自采伐也不错。如果是私人属地当然没有征得同意是不能动一草一木的，但是公园绝大部分是公共财产，这里所能够采摘的食用野菜可以说100%在美国的划分是“WEED"，看看下边关于From Wikipedia关于WEED的定义：简单一句话WEED就是不要的杂草，在花园草地田野WEED是一大害，就只说公园每年都花费大量的人力物力来控制消灭WEED，所以在公园挖野菜是在做好事，在帮助公园做铲除杂草。需要证书才能钓鱼，但除了自然公园之外没有听说过要证书才能挖WEED，就是自然公园需要证书的也是一些稀有或者珍贵的蔬菜或者药材。不知道别误导。至于蚌壳类，各个海滩不一样，大部分地方是可以自由挖采的，个别地方除外。
This article is about plants specifically called weeds. For other uses, see Weed (disambiguation).

Yellow starthistle, a thistle native to southern Europe and the Middle East that is an invasive weed in parts of North America.A weed in a general sense is a plant that is considered by the user of the term to be a nuisance, and normally applied to unwanted plants in human-made settings such as gardens, lawns or agricultural areas, but also in parks, woods and other natural areas. More specifically, the term is often used to describe native or nonnative plants that grow and reproduce aggressively.[1]

Weeds may be unwanted because they are unsightly, or they limit the growth of other plants by blocking light or using up nutrients from the soil. They also can harbor and spread plant pathogens that can infect and degrade the quality of crop or horticultural plants. Weeds may be a nuisance because they have thorns or prickles, cause skin irritation when contacted, or parts of the plants might come off and attach to fur or clothes.