|Vignette of my front border with yellow accents provided by Allium moly and yellow dutch iris|
I particularly like lemon yellow as opposed to a more orange yellow, and two plants which meet this criterion, and are also deer resistant and drought tolerant (which they have to be to exist in this border) are Allium moly and yellow dutch irises. I would highly recommend Allium moly--most bulb suppliers carry it, it is inexpensive and it provides a nice shot of lemon yellow at a time to coincide with the great flower extravaganza in this border. I have had more mixed results with the dutch irises. They are also inexpensive bulbs carried by most bulb suppliers, but I have found that they tend to disappear from the garden over time. I suppose I could remedy this by getting more each year, but I want the plants in this border to be self sustaining over time.
Other plants in the photo above are Eremurus 'Roford', Allium 'Globemaster', Papaver orientale 'Bolero', Eryngium bourgatii, Echium vulgare, Papaver somniferum, and Nasella (Stipa) tenuissima. As you may be able to see from the photo, particularly if you click on it and view it large, the flowers of the Eryngium bourgatii are nothing to write home about.
One plant which would provide a shot of yellow at this time of the year, and that I do not currently grow is any kind of Euphorbia. I have, in the past, grown every kind of Euphorbia that is hardy in our climate, and I have gradually gotten rid of them for one reason or another, so that I am now Euphorbialess. The main reason I don't grow them in this front area anymore is that after the bloom time is over the flowers become incredibly ugly and you have to cut off the flowering stalks to keep the garden looking good. In a garden the size of mine not only is this an onerous chore, but the white sap the cut stems exude can be downright dangerous.