Wrinkles in tear trough only when smiling. Would filler help this?

lasers, peels, and microneedling can help that area. I would suggest at home dermarolling (see eye rolling package from emeragecosmetics.com where we do free skincare consults daily) and peels.
There are many things you can do to treat under eye hollows and dark circles. A surgical option to remove skin and/or fat will be the best long term.  However, non invasive less downtime options such as fillers, lasers, microneedling/PRP, cosmelan peels and stem cells can all help give some improvement. I suggest. You get a formal consultation to see what is best for you and your goals.

I would try some tear trough filler which often can help dark circles assuming there is an actual concavity there. If the results are insufficient, adding a touch of Botox under each eye can be helpful for more dynamic wrinkles such as with smiling. This is a delicate area, so make to only go to an experienced and highly trained physician injector (e.g. dermatologist etc.) for optimal results and safety.

Without seeing your face, I will say that dark circles caused by hollowing can be addressed beautifully with fillers such as Belotero and Juvederm. Often, a small amount of product can result in a big difference! I would also recommend adding a high-quality eye cream if you haven't already  (I'm a huge fan of Neocutis Lumiere products myself).

Hello there, thank you for your question! Sounds like your particular concern could definitely be improved with the addition of some filler under the eyes and on what we call the tear through area which is that junction between the upper part of your nose and your lower eyelid. Keep in mind though that although you are not interested in botox, it also sounds that there is a dynamic component to your concern that would also be improved by the addition of it. The ideal treatment would therefore be a combination of the two, giving you that extra volume in that area while also preventing it from showing up when you smile, giving you that rested, refreshed look. Here in my Houston, TX office i would probably choose Volbella as far as filler for your particular case. Hope this helps!
Best, 
Christian Arroyo, MD

Without photos it is hard to give an opinion.  If the cause of the wrinkles is due to volume loss, causing the skin to bunch up then fillers may help you.  A great place to begin is a visit to a board certified plastic surgeon near you for an evaluation.