There are so many Jonquils out there. I bought one called Oregon Gold that looks similar to this one and continues to bloom in crowded conditions but it was registered in 1973. Nice thing about throwing out names is that you get to see that these various varieties have been shared around the world. In the past bulbs were shared around within local regions after someone mail ordered them and began sharing the ones that survived and multiplied. Keith Kridler Mt. Pleasant, Texas
If the choice is between Sweetness and Trevithian:
Sweetness is a bit earlier. Here is Georgia, it is usually single flowered. Trevithian is a bit later and more often sports 2 or more blooms.
If the choice is between Sweetness and Trevithian: