Wintergreen is Gaultheria procumbens, a very hardy, shade-loving, evergreen groundcover native to woodland areas. It will do best in a woodland setting - partial to full shade and moisture retentive soils. Depending on your location, it could work very well in either of your situations, although if the birch planting affords hot sun in summer now, this may need to wait until the birch is better established and more shade offered. Being in full sun in winter is usually not an issue.

Yes, the berries are edible and were/are consumed by native peoples but I don't find them particularly palatable. They can get very large and make a nice show, specially in winter when they contrast with the ruddy foliage.

This is a very popular groundcover in my area - used heavily in winter cotainer plantings as well - and I sell a lot of it.

I regard Wintergreen as a very choice groundcover. It is always evergreen and neat, never a bad hair day. The berries have the famous wintergreen taste but are kind of mealy and not very abundant, more of a novelty fruit. I had some in a sunny border for a while and it actually seemed to spread better there than in the difficult dry shade under a cedar where it is presently growing and slowly spreading. I moved it because I thought it would get overrun with daylilies. I think it would survive in a sunny location, but maybe you could divide it and split it between the two or eventually divide it for under the birch. I'm about to take a little from my present bed and move it to a sunnier location myself.

Thanks for the info. I think I will plant it in the area with more shade right now and maybe transfer it later to another location. I hope it does well as it is very diferent from the usual groundcovers offered in this area (Zone 5).Thank you for your help!