Old-school style beach plum jelly is made without any added pectin. When gathering them in the wild make sure to include some under-ripe berries. A long simmer makes for a good strong set. It's a sticky jelly with a good puckery punch.
Sour cherries meet their soul mates, tart beach plums. The beach plum jelly base thinkens the cherry jam. The cherries are left whole for a delux presentation. Low sugar pectin keeps things from getting too tame. It's good.
There can't be beach plums in Oregon because otherwise there'd already be an episode of Portlandia dedicated to cult of Beach Plum Jelly: foraged locally, strictly seasonal, old-timey recipe for an odd yet nonthreatening jelly, now with reduced sugar