There are various traders in the UK who produce replica Pilgrimage Badges from the mediaeval period. The most common is beckets Tomb from the pilgrimage trail to Canterbury. Well that is the way that UK'rs wear them. Jerusalem, Compostella and walsingham are all common themes. This book has several photos of pilgrims badges.
Sizes seem to vary, but up to a couple inches.
For doing site tokens, you might want to consider scaled down pieces to save on materials cost. Even though pewter is relatively inexpensive, doing enough for even a modest event will consume a considerable amount of metal. Billy and Charlie make the best badges, but I make some, as well. Also there are the creations of the Fettered Cock. These are probably where people got their scallops.