Edible weeds
Question
My neighbor has edible weeds that sprout around now in her garden, namely wood sorrel (חמציץ, Jerusalemites often call them חמצוץ). Can I eat them during shemitah or are they considered sefichin?
Answer
In short: since wood sorrel is not a type of plant that is planted (it is a weed), it is permitted to eat it during shemitah and is not included under the sefichin prohibition. See below about the rationale, kedushat shevi'it, and how to check wood sorrel for insects.
Expansion:
While eating plants that sprout on their own is biblically permitted, Chazal banned consuming annual plants the sprout during shemitah so that people would not clandestinely plant annuals and claim that they sprouted on their own.
However, certain plants are not intentionally planted for consumption, neither for human or animal consumption. Since this is the case, Chazal did not ban eating such plants.
If next by next shemitah people start planting and growing wood sorrel, they would be considered sefichin.
What about kedushat shevi'it?
While there are different opinions, and some are stringent to treat these weeds with kedushat shevi'it, the ruling of the rabbis of Torah VeHa'aretz Institute is that one can be lenient and handle them regularly.
Make sure that you check them thoroughly for insects, by soaking them in soapy water, rubbing each leaf, and checking against sunlight.