Theressa and I foraged some more this evening. Last year we identified three Cornus mas (Cornelian cherry) trees at the local park, but we found them too late in the season to really get a taste test. This year we checked on them about a month too early, and then not until tonight, about a month too late on two of them, but in time to harvest half a pound or so from the third!
The fruits we got taste very tart. I would have trouble eating a lot of them at a time. I think the fruits ripened fully on the tree, as many of them had fallen to the ground already , and those remaining came off very easily with just a gently tug (or inadvertently when we brushed a branch too hard!) Theressa harvested many from the ground; the ones I tried from the ground tasted slightly fermented, which I don't like, but Theressa doesn't mind.
Lee Reich says in Uncommon Fruits for Every Garden that "ripe fruits left to hang on the tree become more concentrated in flavor and sweetness. Some people prefer to allow harvested fruit to sit at room temperature for a day or more, in which case the flavor becomes sweet, but more sedate." We'll see whether our fruits sweeten up at all as we graze on them bit by bit the next day or two.
Reich also says that when the fruit was popular in Britain, only rarely did people eat them straight because sweeter varieties had not been selected. Usually they made tarts, sweetened syrups, or added the juice to cider and perry. I assume we did not find varieties chosen for taste; presumably our trees either grew from seed or came from an ornamental selection. So I still feel curious to try some of the other varieties One Green World sells, to compare the flavor and sweetness to those in the park.