They aren't "pretty" but the best treat I've found is grape vines. I planted a couple small potted "concord" vines that really took off. They are 3-4 years old now and have spread roughly 15ft in both directions. I have them growing on top of a chain link fence dog kennel. They produced pounds and pounds of fresh treats from the beginning of August through October. I froze several gallon zip locks to give them in the winter. My birds start jumping up and eating grapes before theyre even ripe. After they do ripen, I either collect them or they just fall off and get eaten.
They provide nice shade in the summer as well. They grow large 6" leaves that attracts lots of bugs too.
Great Idea!