They hate most species of Euphorbia, Leslie.

Try Fritillaria imperialisis.

In the northern hemisphere, flowering takes place in late April or May, accompanied by a distinctly foxy odour that repels mice, moles, and other rodents.

Here's what I wrote about Euphorbia and moles in 2008

'A visitor said that Euphorbia roots give off a gas which is toxic to moles and planting it around the perimeter of a garden will keep moles away. This claim is much discussed in Internet blogs with some people swearing by its efficacy and others saying it made no difference to their mole or gopher problems. Euphorbia lathyris, (Caper spurge, Mole plant, Sassy jack) is alleged to have seed heads that explode and make a bang that scares moles.'

Castor plant is the most dreded species for gophers and Moles. It is a poisonus plant.

Well, I don't know about poison gas or loud bangs, but most--but not all--species of Euphorbia have a caustic sap, so gophers don't like to burrow through their roots. Just ask anyone who has run afoul of the above ground parts of a Euphorbia rigida!