Wild bees and other insects will pollinate your crops, but they need pollen and nectar to keep them going until your plants start flowering, and afterwards until the queens go into hibernation in the autumn, You can find a list of some flowering plants and shrubs that are useful to bee, compiled by one of our members here. The important thing to remember is that double flowers and other highly bred garden varieties are unlikely to be good for wildlife because they either have no pollen or nectar or it is too difficult to get at. Many wild flowers could be added to the list from your own observations as to what you see bees feeding on. Dandelions are especially rich in bee food so do let them flower before you dig them up.
If you’d like to do more, the Wildlife Trusts have lots of useful information about wildlife friendly gardening at www.wildlifetrusts.org/gardening.