No Truce with Kings
The Longest Voyage
The Sharing of Flesh
The Queen of Air and Darkness
Goat Song

Original appearances from 1960 to 1973: 3 from Magazine of F&SF, and Analog, Galaxy. All 5 won the Hugo award for "best short fiction" or "best novelet" or "best novella." The last 2 also won the Nebula award for best novella/novelet. All of these have appeared in Poul Anderson collections before, so I would not really recommend this for people who are already big fans of his work - but it would make an excellent introduction to show why Anderson was considered one of the biggest names in SF.