can you post a pic.. words dont really do it for me....

is it a glazed ceramic that is winter proof.. frankly.. i would remove everything for winter ... as a failsafe to the pot not cracking.. so your hardiness requirements would be un-necessary ...

ken

btw I have a nice blue pot with some yellow variegated acorus (a yellow grass-type plant) in it.... looks nice but I put it under shelter for the winter. The yellow-blue is a nice combo

The plant that is most often sold for container plantings all up and down the west coast that fits your description is a dwarf conifer - Cupressus macrocarpa 'Wilma Goldcrest'. While it does have an upright and almost columnar habit, it pooches out at the base......kinda dumpling shaped, as it were :-) This plant is sometimes referred to as the lemon-lime cypress as not only is it that color (a bright chartreusey lime green) but it also smells strongly of lemon-lime soda when the floliage is brushed.

It is fully hardy to zone 7 - even in a container - as long as you keep it out of direct winter winds. In fact, it is reported hardy without cold damage down to 5F. And make sure you have a very textural, barky potting soil that doesn't hold excess moisture in winter.

but we need to know if it has drainage.. not many conifers prefer a sodden medium ....

and which of the media you select will really matter..

ken

I concur, nice pot!

My two favorite choices would be:
Spirea Ogon AKA mellow yellow, which is fountain shaped rather than the rounded or bun shape of many spireas. White flowers, fine willowy yellow to chartreuse summer foliage, and red-gold fall color.
Clematis Stolwijk Gold, which has gold to chartreuse leaves and early blue flowers. Grown on a medium trellis I think this would look stunning.

Ninebark I think will be too big for the pot based on my P. coppertina. I'm personally not a fan of privet and IME they get pretty huge also.

Some other thoughts:
Yellow oak leaf hydrangea, Little Honey, though it has a reputation for being a bit fussy. It likes at least part shade
Yellow-variegated shrub dogwoods (Cornus), though they might be too large
Yellow elderberries (Sambucus) might stay small enough in your pot though they get large in the ground
Clumping bamboos, though I am not sure if any of the yellowish ones will be hardy enough for you.
Yellow leaved evergreens, such as some of the Chamaecyparis, would have foliage year round if you will be leaving the pot outside.
Some heathers have yellow to gold to orange foliage depending on the time of year and the variety.
Caryopteris such as Sunshine Blue have gold foliage and late season blue flowers. You'd need to check if the flowers coordinated with the pot.
Gold grasses, either variegated like some of the Miscanthus, or solid like gold Hakone grass.

You might also want to consider a water garden in your pot with papyrus, though it wouldn't be hardy or yellow.

Then in summer underplant it with a Dragon Wing Begonia -- which will spill over the sides. The combo of red blooms with the euonymus leaves will be stunning. -- or maybe Fuschia if that does better in your area?

I guess it depends on where you're putting your container and what 'shape' you want in it.

E. japonicus 'Chollipo' can be kept open or clipped into a more compact shape. I'd say you could keep it into a round shape or upright oval. Sort of your call.

Here where I work they planted 'Silver King' euonymus in containers year-round and then underplant with red wax begonias in summer ; pansies in winter. Looks nice. Silver King is more green and white. I think with that pot you'd want more gold.

If you are interested in a more spreading variegated euonymus, you could try to find one called Euonymus fortunei 'Sunspot'. It tends to trail. But you wont' be able to plant anything else under it or next to it. It would eventually form a wide oval shape. New growths would need occasional trimming.

E. 'Moonshadow' is more a ground cover.