Hey oh
Oo this is a fun plant. Yes, the leaves are high in oxalic acid. While nice and zingy, it takes a long time for your body to eliminate it. There is a clover plant I eat that is also high in this and th servings are very smal and limited to once a week.
As to the plant stalks, they are eadable all year. However, as the season warms up, the taste of this plant changes, and there are many people that don't like it late season. The way I explain it is thus, early season can be eaten as is, late season NEEDS to be well sugared. :D Now, also with sugaring it, if you dice up the stems, and sugar them, and let them sit for a few hours, they will liquify into a nice syrup which is very nice on vanilla ice cream. :D :D
Also, it is rather easy to grow. My grandmother, and my father, and myself, we all grow ours in the gardens scrub corners. Against telephone poles, beside the composter etc.